couchapp+evently: _init/data.js and $$(this) - couchapp

I'm reading the couchapp tutorial http://couchapp.org/page/evently-do-it-yourself-ii-state and am confused on two points (I don't like being told answers without knowing why they are what they are):
$ cat data.js
function(e) {
$$(this).toppings = [];
}
What's the "e" parameter in data.js?
What exactly does the $$(this) function return, and how do I find out more about it? Is it solely user-definable state, or are there methods or special state parameters that I need to know about?

You can find more about $$() in this post from wycats, as reported in the sources.
I don't use Evently any more, so I don't remember what the e parameter is. However you can easily check it using Firebug.

Related

Unable to use pickAFile in TigerJython

In JES, I am able to use:
file=pickAFile()
In TigerJython, however, I get the following error
NameError: name 'pickAFile' is not defined
What am I doing wrong here?
You are not doing anything wrong at all. The thing is that pickAFile() is not a standard function in Python. It is actually rather a function that JES has added for convenience, but which you probably will not find it in any other environment.
Since TigerJython and JES are both based on Jython, you can easily write a pickAFile() function on your own that uses Java's Swing. Here is a possible simple implementation (the pickAFile() found in JES might be a bit more complex, but this should get you started):
def pickAFile():
from javax.swing import JFileChooser
fc = JFileChooser()
retVal = fc.showOpenDialog(None)
if retVal == JFileChooser.APPROVE_OPTION:
return fc.getSelectedFile()
else:
return None
Given that it is certainly a useful function, we might have to consider including it into our next update of TigerJython.
P.S. I would like to apologise for answering so late, I have just joined SO recently and was not aware of your question (I am one of the original authors of TigerJython).

Generating Random String of Numbers and Letters Using Go's "testing/quick" Package

I've been breaking my head over this for a few days now and can't seem to be able to figure it out. Perhaps it's glaringly obvious, but I don't seem to be able to spot it. I've read up on all the basics of unicode, UTF-8, UTF-16, normalisation, etc, but to no avail. Hopefully somebody's able to help me out here...
I'm using Go's Value function from the testing/quick package to generate random values for the fields in my data structs, in order to implement the Generator interface for the structs in question. Specifically, given a Metadata struct, I've defined the implementation as follows:
func (m *Metadata) Generate(r *rand.Rand, size int) (value reflect.Value) {
value = reflect.ValueOf(m).Elem()
for i := 0; i < value.NumField(); i++ {
if t, ok := quick.Value(value.Field(i).Type(), r); ok {
value.Field(i).Set(t)
}
}
return
}
Now, in doing so, I'll end up with both the receiver and the return value being set with random generated values of the appropriate type (strings, ints, etc. in the receiver and reflect.Value in the returned reflect.Value).
Now, the implementation for the Value function states that it will return something of type []rune converted to type string. As far as I know, this should allow me to then use the functions in the runes, unicode and norm packages to define a filter which filters out everything which is not part of 'Latin', 'Letter' or 'Number'. I defined the following filter which uses a transform to filter out letters which are not in those character rangetables (as defined in the unicode package):
func runefilter(in reflect.Value) (out reflect.Value) {
out = in // Make sure you return something
if in.Kind() == reflect.String {
instr := in.String()
t := transform.Chain(norm.NFD, runes.Remove(runes.NotIn(rangetable.Merge(unicode.Letter, unicode.Latin, unicode.Number))), norm.NFC)
outstr, _, _ := transform.String(t, instr)
out = reflect.ValueOf(outstr)
}
return
}
Now, I think I've tried just about anything, but I keep ending up with a series of strings which are far from the Latin range, e.g.:
𥗉똿穊
𢷽嚶
秓䝏小𪖹䮋
𪿝ท솲
𡉪䂾
ʋ𥅮ᦸ
堮𡹯憨𥗼𧵕ꥆ
𢝌𐑮𧍛併怃𥊇
鯮
𣏲𝐒
⓿ꐠ槹𬠂黟
𢼭踁퓺𪇖
俇𣄃𔘧
𢝶
𝖸쩈𤫐𢬿詢𬄙
𫱘𨆟𑊙
欓
So, can anybody explain what I'm overlooking here and how I could instead define a transformer which removes/replaces non-letter/number/latin characters so that I can use the Value function as intended (but with a smaller subset of 'random' characters)?
Thanks!
Confusingly the Generate interface needs a function using the type not a the pointer to the type. You want your type signature to look like
func (m Metadata) Generate(r *rand.Rand, size int) (value reflect.Value)
You can play with this here. Note: the most important thing to do in that playground is to switch the type of the generate function from m Metadata to m *Metadata and see that Hi Mom! never prints.
In addition, I think you would be better served using your own type and writing a generate method for that type using a list of all of the characters you want to use. For example:
type LatinString string
const latin = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz01233456789"
and then use the generator
func (l LatinString) Generate(rand *rand.Rand, size int) reflect.Value {
var buffer bytes.Buffer
for i := 0; i < size; i++ {
buffer.WriteString(string(latin[rand.Intn(len(latin))]))
}
s := LatinString(buffer.String())
return reflect.ValueOf(s)
}
playground
Edit: also this library is pretty cool, thanks for showing it to me
The answer to my own question is, it seems, a combination of the answers provided in the comments by #nj_ and #jimb and the answer provided by #benjaminkadish.
In short, the answer boils down to:
"Not such a great idea as you thought it was", or "Bit of an ill-posed question"
"You were using the union of 'Letter', 'Latin' and 'Number' (Letter || Number || Latin), instead of the intersection of 'Latin' with the union of 'Letter' and 'Number' ((Letter || Number) && Latin))
Now for the longer version...
The idea behind me using the testing/quick package is that I wanted random data for (fuzzy) testing of my code. In the past, I've always written the code for doing things like that myself, again and again. This meant a lot of the same code across different projects. Now, I could of course written my own package for it, but it turns out that, even better than that, there's actually a standard package which does just about exactly what I want.
Now, it turns out the package does exactly what I want very well. The codepoints in the strings which it generates are actually random and not just restricted to what we're accustomed to using in everyday life. Now, this is of course exactly the thing which you want in doing fuzzy testing in order to test the code with values outside the usual assumptions.
In practice, that means I'm running into two problems:
There's some limits on what I would consider reasonable input for a string. Meaning that, in testing the processing of a Name field or a URL field, I can reasonably assume there's not going to be a value like 'James Mc⌢' (let alone 'James Mc🙁') or 'www.🕸site.com', but just 'James McFrown' and 'www.website.com'. Hence, I can't expect a reasonable system to be able to support it. Of course, things shouldn't completely break down, but it also can't be expected to handle the former examples without any problems.
When I filter the generated string on values which one might consider reasonable, the chance of ending up with a valid string is very small. The set of possible characters in the set used by the testing/quick is just so large (0x10FFFF) and the set of reasonable characters so small, you end up with empty strings most of the time.
So, what do we need to take away from this?
So, whilst I hoped to use the standard testing/quick package to replace my often repeated code to generate random data for fuzzy testing, it does this so well that it provides data outside the range of what I would consider reasonable for the code to be able to handle. It seems that the choice, in the end, is to:
Either be able to actually handle all fuzzy options, meaning that if somebody's name is 'Arnold 💰💰' ('Arnold Moneybags'), it shouldn't go arse over end. Or...
Use custom/derived types with their own Generator. This means you're going to have to use the derived type instead of the basic type throughout the code. (Comparable to defining a string as wchar_t instead of char in C++ and working with those by default.). Or...
Don't use testing/quick for fuzzy testing, because as soon as you run into a generated string value, you can (and should) get a very random string.
As always, further comments are of course welcome, as it's quite possible I overlooked something.

JSON issue with SQL lines return

I have an issue when I try to parse my JSON. I create my JSON "by my hand" like this in PHP :
$outp ='{"records":['.$outp.']}'; and I create it so I can take field from my database to show them in the page. The thing is, in my database I have a field "description" where people can give a description about something. So some people make return to line like this for example :
Interphone
Equipe:
Canape-lit
Autre:
Local
And when I try to parse my JSON there is an error because of these line's return. "SyntaxError: Unexpected token".
Here's an example of my JSON :
{"records":[{"Parking":"Aucun","Description":"Interphone
Equipé :
Canapé-lit
","Chauffage":"Fioul"}]}
Can someone help me please ?
You've really dug yourself into a very bad hole here.
The problem
The problem you're running into is that a newline (line feed and carriage return characters) are not valid JSON. They must be escaped as \n and \r. You can see the full JSON standard here here.
You need to do two things.
Fix your code
In spite of the fact that the JSON standard is comparatively simple, you should not create your JSON by hand. You already know why. You have to handle several edge cases and the like. Your users could enter anything on the page, and you need to make sure that it gets properly encoded no matter what.
You need to use a JSON serialization tool. json_encode is built in as of 5.2. If you can't use this for any reason, find an existing, widely used (and therefore heavily tested) third party library with a JSON serializer.
If you're asking, "Why can't I create my own serializer?", you could, in theory. Realistically, there is no point. Yours won't be better than existing ones. It will be much more likely to have bugs and to perform worse than something a lot of people have used in production. It will also take much longer to create and test than using an existing one.
If you need this data in code after you pull it back out of the database, then you need a JSON deserializer. json_decode should also be fine, but again, if you can't use it, look for a widely used third party library.
Fix your data
If you haven't hit production yet, you have really dodged a bullet here, and you can skip this whole section. If you have gone to production and you have data from users, you've got a major problem.
Even after you fix your code, you still have bad data in your production database that won't parse correctly. You have to do something to make this data usable. Unfortunately, it is impossible to automatically recover the original data for every possible case. This is because users might have entered the characters/substrings you added to the data to turn it into "JSON"; for example, they might have entered a comma separated list of quoted words: "dog","cat","pig", and "cow". That is an intractable problem, since you know for a fact you didn't properly serialize all your incoming input. There's no way to tell the difference between text your code generated and text the user entered. You're going to have to settle for a best effort and try to throw errors when you can't figure it out in code, and it might mess up a user's data in some special cases. You might have to fix some things manually.
Start by discussing this with your manager, team lead, whoever you answer to. Assuming that you can't lose the data, this is the most sound process to follow for creating a fix for your data:
Create a database dump of your production data.
Import that dump into a development database.
Develop and test your method of repairing this data against the development database from the last step.
Ensure you have a recovery plan for deployments gone wrong. Test this plan in your testing environment.
Once you've gone through your typical release process, it's time to release the fixed code and the data update together.
Take the website offline.
Back up the database.
Update the website with the new code.
Implement your data fix.
Verify that it worked.
Bring the site online.
If your data fix doesn't work (possibly because you didn't think of an edge case or something), then you have a nice back up you can restore and you can cancel the release. Then go back to step 1.
As for how you can fix the data, I don't recommend queries here. I recommend a little script tool. It would have to load the data from the database, pull the string apart, try to identify all the pieces, build up an object from those pieces, and finally serialize them to JSON correctly, and put them back into the database.
Here's an example function of how you might go about pulling the string apart:
const ELEMENT_SEPARATOR = '","';
const PAIR_SEPARATOR = '":"';
function recover_object_from_malformed_json($malformed_json, $known_keys) {
$tempData = substr($malformed_json, 14); // Removes {"records":[{" prefix
$tempData = substr($tempData, 0, -4); // Removes "}]} suffix
$tempData = explode(ELEMENT_SEPARATOR, $tempData); // Split into what we think are pairs
$data = array();
$lastKey = NULL;
foreach ($tempData as $i) {
$explodedI = explode(KEY_VALUE_SEPARATOR, $i, 2); // Split what we think is a key/value into key and value
if (in_array($explodedI[0], $known_keys)) { // Check if it's actually a key
// It's a key
$lastKey = $explodedI[0];
if (array_key_exists($lastKey, $data)) {
throw new RuntimeException('Duplicate key: ' + $lastKey);
}
// Assign the value to the key
$data[$lastKey] = $explodedI[1];
}
else {
// This isn't a key vlue pair, near as we can tell
// So it must actually be part of the last value,
// and the user actually entered the delimiter as part of the value.
if (is_null($lastKey)) {
// This one is REALLY messed up
throw new RuntimeException('Does not begin with a known key');
}
$data[$lastKey] += ELEMENT_SEPARATOR;
$data[$lastKey] += $i;
}
}
return $data;
}
Note that I'm assuming that your "list" is a single element. This gets much harder and much messier if you have more than one. You'll also need to know ahead of time what keys you expect to have. The bottom line is that you have to undo whatever your code did to create the "JSON", and you have to do everything you can to try to not mess up a user's data.
You would use it something like this:
$knownKeys = ["Parking", "Description", "Chauffage"];
// Fetch your rows and loop over them
foreach ($dbRows as $row) {
try {
$dataFromDb = $row.myData // or however you would pull out this string.
$recoveredData = recover_object_from_malformed_json($dataFromDb);
// Save it back to the DB
$row.myData = json_encode($recoveredData);
// Make sure to commit here.
}
catch (Exception $e) {
// Log the row's ID, the content that couldn't be fixed, and the exception
// Make sure to roll back here
}
}
(Forgive me if the database stuff looks really wonky. I don't do PHP, so I have no idea how that code should look. Hopefully, you can at least get the concept.)
Why I don't recommend trying to parse your data as JSON to recover it.
The bottom line is that your data in the database is not JSON. IF you try to parse it as such, all the other edge cases you didn't handle properly will get screwed up in the process. You'll see bad things like
\\ becomes \
\j becomes j
\t becomes a tab character
In the end, it will just mess up your data even more.
Conclusion
This is a huge mess, and you should never try to convert something into a standard format without using a properly built, well tested serializer. Fixing the data is going to be hard, and it's going to take time. I also seriously doubt you have a lot of background in text processing techniques, and lacking that knowledge is going to make this harder. You can get some good info on text processing by studying how compilers are made. Good luck.

calling script_execute with a variable

I'm using GameMaker:Studio Pro and trying to execute a script stored in a variable as below:
script = close_dialog;
script_execute(script);
It doesn't work. It's obviously looking for a script named "script". Anyone know how I can accomplish this?
This question's quite old now, but in case anyone else ends up here via google (as I did), here's something I found that worked quite well and avoids the need for any extra data structures as reference:
scriptToCall = asset_get_index(scr_scriptName);
script_execute(scriptToCall);
The first line here creates the variable scriptToCall and then assigns to it Game Maker's internal ID number for the script you want to call. This allows script_execute to correctly find the script from the ID, which doesn't work if you try to pass it a string containing the script name.
I'm using this to define which scripts should be called in a particular situation from an included txt file, hence the need to convert a string into an addressable script ID!
You seem to have some confusion over how Game Maker works, so I will try to address this before I get around to the actual question.
GML is a rather simple-minded beast, it only knows two data types: strings and numbers. Everything else (objects, sprites, scripts, data structures, instances and so on) is represented with a number in your GML code.
For example, you might have an object called "Player" which has all kinds of fancy events, but to the code Player is just a constant number which you can (e.g.) print out with show_message(string(Player));
Now, the function script_execute(script) takes as argument the ID of the script that should be executed. That ID is just a normal number. script_execute will find the script with that ID in some internal table and then run the script.
In other words, instead of calling script_execute(close_dialog) you could just as well call script_execute(14) if you happened to know that the ID of close_dialog is 14 (although that is bad practice, since it make the code difficult to understand and brittle against ID changes).
Now it should be obvious that assigning the numeric value of close_dialog to a variable first and then calling script_execute on that variable is perfectly OK. In the end, script_execute only cares about the number that is passed, not about the name of the variable that this number comes from.
If you are thinking ahead a bit, you might wonder whether you need script_execute at all then, or if you could instead just do this:
script = close_dialog;
script();
In my opinion, it would be perfectly fine to allow this in the language, but it does not work - the function call operator actually does care about the name of the thing you try to call.
Now with that background out of the way, on to your actual question. If close_dialog is actually a script, your suggested code will work fine. If it is an extension function (or a built-in function -- I don't own Studio so what do I know) then it does not actually have an ID, and you can't call it with script_execute. In fact, you can't even assign close_dialog to a variable then because it does not have any value in GML -- all you can do with it then is call it. To work around this though, you could create a script (say, close_dialog_script which only calls close_dialog, which you can then use just as above.
Edit: Since it does not seem to work anyway, check whether you have a different resource by the name of close_dialog (perhaps a button sprite). This kind of conflict could mean that close_dialog gives you the ID of the sprite, not of the script, while calling the script directly would still work.
After much discussion on the forums, I ended up going with this method.
I wrote a script called script_id()
var sid;
sid = 6; //6 = scriptnotfound script :)
switch (argument0) {
case "load_room":
sid = 0;
break;
case "show_dialog":
sid = 1;
break;
case "close_dialog":
sid = 3;
break;
case "scrExample":
sid = 4;
break;
}
return sid;
So now I can call script_execute(script_id("close_dialog"));
I hate it, but it's better than keeping a spreadsheet... in my opinion.
There's also another way, with execute_string();
Should look like this:
execute_string(string(scriptName) + "();");

naming a function that exhibits "set if not equal" behavior

This might be an odd question, but I'm looking for a word to use in a function name. I'm normally good at coming up with succinct, meaningful function names, but this one has me stumped so I thought I'd appeal for help.
The function will take some desired state as an argument and compare it to the current state. If no change is needed, the function will exit normally without doing anything. Otherwise, the function will take some action to achieve the desired state.
For example, if wanted to make sure the front door was closed, i might say:
my_house.<something>_front_door('closed')
What word or term should use in place of the something? I'd like it to be short, readable, and minimize the astonishment factor.
A couple clarifying points...
I would want someone calling the function to intuitively know they didn't need to wrap the function an 'if' that checks the current state. For example, this would be bad:
if my_house.front_door_is_open():
my_house.<something>_front_door('closed')
Also, they should know that the function won't throw an exception if the desired state matches the current state. So this should never happen:
try:
my_house.<something>_front_door('closed')
except DoorWasAlreadyClosedException:
pass
Here are some options I've considered:
my_house.set_front_door('closed')
my_house.setne_front_door('closed') # ne=not equal, from the setne x86 instruction
my_house.ensure_front_door('closed')
my_house.configure_front_door('closed')
my_house.update_front_door('closed')
my_house.make_front_door('closed')
my_house.remediate_front_door('closed')
And I'm open to other forms, but most I've thought of don't improve readability. Such as...
my_house.ensure_front_door_is('closed')
my_house.conditionally_update_front_door('closed')
my_house.change_front_door_if_needed('closed')
Thanks for any input!
I would use "ensure" as its succinct, descriptive and to the point:
EnsureCustomerExists(CustomerID)
EnsureDoorState(DoorStates.Closed)
EnsureUserInterface(GUIStates.Disabled)
Interesting question!
From the info that you have supplied, it seems to me that setstate (or simply set, if you are setting other things than states) would be fine, though ensure is good if you want to really emphasize the redundancy of an if.
To me it is however perfectly intuitive that setting a state does not throw an exception, or require an if. Think of setting the state of any other variable:
In C:
int i;
i = 5; // Would you expect this to throw an exception if i was already 5?
// Would you write
if (i != 5)
i = 5;
// ?
Also it only takes about one sentence to document this behaviour:
The function does nothing if the
current state equals the requested
state.
EDIT: Actually, thinking about it, if it is really important to you (for some reason) that the user is not confused about this, I would in fact pick ensure (or some other non-standard name). Why? Because as a user, a name like that would make me scratch my head a bit and look up the documentation ("This is more than just an ordinary set-function, apparently").
EDIT 2: Only you know how you design your programs, and which function name fits in best. From what you are saying, it seems like your setting functions sometimes throw exceptions, and you need to name a setting function that doesn't - e.g. set_missile_target. If that is the case, I think you should consider the set_if, set_when, set_cond or cond_set names. Which one would kind of depend on the rest of your code. I would also add that one line of documentation (or two, if you're generous), which clarifies the whole thing.
For example:
// Sets missile target if current target is not already the requested target,
// in which case it does nothing. No exceptions are thrown.
function cond_set_missile_target ()
or function cond_set_MissileTarget ()
or function condSet_MissileTarget ()
or function condSetMissileTarget ()
ensure is not so bad, but to me it implies only that there is additional logic required to set the state (e.g. multiple states tied together, or other complications). It helps to make the user avoid adding unnecessary ifs, but it does not help much with the exception issue. I would expect an ensure function to throw an exception sooner than a set function, since the ensure function clearly has more responsibilities for, well, ensuring that this setting operation is in fact done right.
I'd go for ensure for the function you describe. I'd also use camelCase, but I suppose you may be in a language that prefers underscores.
You could always document (shock!) your API so that others don't make the mistakes you describe.