Custom parameters in a CDE/CTools dashboard are great for defaulting initial values of parameters, e.g. setting a date parameter to today. i.e. the parameter looks like:
function() {
// some code
return val
}
However there is an issue with them. The first time you access a "custom parameter" in code, it is a function not a string. So you have to use:
paramName()
To get its value.
Once the end user selects a value then you have to use
paramName
This is really awkward in complicated dashboards with lots of prompts. Is there a better way this can be done? (Perhaps there is something in javascript I'm missing to help here?)
OK, there is a solution, but I dont like it!
First; Move all the init code into named procedures e.g.
function monthInit() {
return "june";
}
Then in the custom parameter for month, just say:
monthInit();
That way the custom parameter is always a string, and never starts off as a function.
Not ideal though because then all your init code is in a separate bit of js.
Related
Let's say I have a type of object in my game called oCharacter. All characters must have names, so I want to provide one when I construct the object. I can do that by using the _variables argument of instance_create_layer:
instance_create_layer(0, 0, "Instances", oCharacter, { name: "George" });
I could even make sure that I don't forget to do this by making a "constructor" function for characters and only instantiating them using that:
function character_create(_x, _y, _name) {
return instance_create_layer(_x, _y, "Instances", oCharacter, { name: _name });
}
But this approach has two problems.
The first is that I or another developer might forget about this convention and instantiate a character directly using instance_create_layer, forgetting to pass a name and setting up a runtime error further down the road.
The second (related) issue is that Feather doesn't know about this convention, so my Feather window is full of error messages about references to instance variables that aren't declared in the Create event - but I don't see how I can declare these variables in the Create event, as I'm expecting their value to be provided by the creator.
Is there some way of doing this that addresses these issues?
The first problem is just about setting rules about the code conventions within your team, if your team does not know about these conventions you want them to follow, then you should tell it them in a meeting.
For the second problem: Maybe you could create an empty/nullable variable in the Create Event? I'm afraid I'm not familiar with Feather
Personally I would do two things for this.
Create development standards for the team and put them in something like a Word document, wiki page, onenote, whatever makes the most sense for your team.
I would use a function to create the instance of the object (like you're doing there), and have some simple validation checks inside of the create event itself that will cancel it's creation (something like a guard clause) and output a debug message with a reminder.
It's not the most elegant solution but that should do the trick (assuming you haven't found something else by now haha)
One common problem we have in our codebase is that people forget to check if a list is empty before using it in an in clause.
For example (in Scala with Anorm):
def exists(element: String, list: List[String]): Boolean =
SQL("select {element} in {list} as result")
.on('element -> element, 'list -> list)
.as(SqlParser.bool("result").single)
This code works perfectly well as long as list has at least one element.
If it has 0 elements, you get a syntax error, which is weird if you're used to other programming languages that would allow this empty list case.
So, my question is: what's the best way to prevent this error from happening?
Initially, we did this:
def exists(element: String, list: List[String]): Boolean =
if (list.nonEmpty) {
SQL("select {element} in {list} as result")
.on('element -> element, 'list -> list)
.as(SqlParser.bool("result").single)
} else {
false
}
This works perfectly well, and has the added advantage that it doesn't hit the database at all.
Unfortunately, we don't remember to do this every time, and it seems that 1-2 times a month we're fixing an issue related to this.
An alternate solution we came up with was to use a NonEmptyList class instead of a standard List. This class must have at least one element. This works excellent, but again, people have not been diligent with always using this class.
So I'm wondering if there's an approach I'm missing that prevent this type of error better?
It looks like you've already found a way to resolve this problem - you have an exists() function which handles an empty list cleanly. The problem is that people are writing their own exists() functions which don't do that.
You need to make sure that your function is accessible as a utility function, so that you can reuse it whenever you need to, rather than having to rewrite the function.
Your problem is an encapsulation problem: the Anorm API is like an open flame and people can burn themselves. If you rely just on people to take precautions, someone will get burnt.
The solution is to restrict the access to the Anorm API to a limited module/package/area of your code:
Anorm API will be private and accessible only from very few places, where it is going to be easy to perform the necessary controls. This part of the code will expose an API
Every other part of the code will need to go through that API, effectively using Anorm in the "safe" way
I like to try to optimize my code, and I would like to measure the time taken by a function.
I have a class named Chrono. So I just have to add chrono.start at the beginning of the function, and chrono.stop at the end. My class chan also add the times it measure in a list, to then have average time, total time...
It works. Only problem is when there is exit sub or return in the middle of the function. Not really a problem, I just add a Try at the begginf of the function, and put my chrono.stop in the finally portion. I'm not sure it's really efficient, but it works.
So here is my question : I would like to have a function taking function name as parameter, that will automatically launch and stop my class when this function is called. I have heard of Reflection, but I have no idea how to use it. And it's really hard to search for this question in the internet (because the words are too common : "do something at the end of a function")
To resume, my code works, no problem. It's just constraining to add code to a function for just a short period of time (and sometimes forgot to remove it).
Thx (I'm french and hope I'm understandable)
This is how you can use reflection to call a method by name:
using System.Reflection;
public int InvokeMethod(string name)
{
int time1 = 1; //call your chrono.start here.
Type thisType = this.GetType();
MethodInfo theMethod = thisType.GetMethod(name);
theMethod.Invoke(this, new object[] { 1 });
int time2 = 10; //call your chrono.end here.
return time2 - time1;
}
However, there is a problem. How will you know what parameters to pass to the function? In the code above, I'm passing the integer 1 (new object[] { 1 }) just for example. So this code cannot be automated, but if you run it manually against each function one by one, then you can change that line to pass the correct arguments and make it work without having to modify your function.
This is to answer your question as how to call a function by name using reflection. However, it is much easier to call it using a delegate (or Fuc<T, tRsult> in .Net v3.5 and higher).
I'm currently working on my first major project in clojure and have run into a question regarding coding style and the most "clojure-esque" way of doing something. Basically I have a function I'm writing which takes in a data structure and a template that the function will try to massage the data structure into. The template structure will look something like this:
{
:key1 (:string (:opt :param))
:key2 (:int (:opt :param))
:key3 (:obj (:tpl :template-structure))
:key4 (:list (:tpl :template-structure))
}
Each key is an atom that will be searched for in the given data structure, and it's value will be attempted to be matched to the type given in the template structure. So it would look for :key1 and check that it's a string, for instance. The return value would be a map that has :key1 pointing to the value from the given data structure (the function could potentially change the value depending on the options given).
In the case of :obj it takes in another template structure, and recursively calls itself on that value and the template structure, and places the result from that in the return. However, if there's an error I want that error returned directly.
Similarly for lists I want it to basically do a map of the function again, except in the case of an error which I want returned directly.
My question is what is the best way to handle these errors? Some simple exception handling would be the easiest way, but I feel that it's not the most functional way. I could try and babysit the errors all the way up the chain with tons of if statements, but that also doesn't seem very sporting. Is there something simple I'm missing or is this just an ugly problem?
You might be interested in schematic, which does pretty similar stuff. You can see how it's used in the tests, and the implementation.
Basically I defined an error function, which returns nil for correctly-formatted data, or a string describing the error. Doing it with exceptions instead would make the plumbing easier, but would make it harder to get the detailed error messages like "[person: [first_name: expected string, got integer]]".
I'd like to use UUID as action parameters. However, unless I use .toString() on the UUID objects when generating the action URL's, Play seems to serialize the object differently; Something like this: referenceId.sequence=-1&referenceId.hashCode=1728064460&referenceId.version=-1&referenceId.variant=-1&referenceId.timestamp=-1&referenceId.node=-1
However, using toString "works", but when I redirect from one action to another by simply invoking the method directly, there's no way I can call toString, as the method expects a UUID. Therefore it gives me the representation shown above.
Is there any way I can intersect the serialization of a certain type?
aren't you able to just use string in your action parameter? you know that this string is an UUID, so you can always recreate UUID from it. Maybe this is not the solution for you but that's my first thought. As far as I know play serializes objects like that when passing them trough paremeters.
If this does not work for you try finding something here: http://www.playframework.org/documentation/1.2.4/controllers
I found a way to do this, but right now it means hacking a part of the frameworks code itself.
What you basically need is a TypeBinder for binding the value from the String to the UUID
and a small code change in
play/framework/src/play/data/binding/Unbinder.java
if (!isAsAnnotation) {
// We want to use that one so when redirecting it looks ok. We could as well use the DateBinder.ISO8601 but the url looks terrible
if (Calendar.class.isAssignableFrom(src.getClass())) {
result.put(name, new SimpleDateFormat(I18N.getDateFormat()).format(((Calendar) src).getTime()));
} else {
result.put(name, new SimpleDateFormat(I18N.getDateFormat()).format((Date) src));
}
}
}
//here's the changed code
else if (UUID.class.isAssignableFrom(src.getClass()))
{
result.put(name, src.toString());
}
else {
// this code is responsible for the behavior you're seeing right now
Field[] fields = src.getClass().getDeclaredFields();
for (Field field : fields) {
if ((field.getModifiers() & BeanWrapper.notwritableField) != 0) {
// skip fields that cannot be bound by BeanWrapper
continue;
}
I'm working with the framework authors on a fix for this. will come back later with results.
if you need this urgently, apply the change to the code yourself and rebuild the framework by issuing
ant
in the playframework/framework
directory.