I'm trying to create a dispatcher of functions in Rebol 3, so that for each string the program receives there's an associated function to be called.
For example:
handlers: make map! [
"foo" foo-func
"bar" bar-func
]
where foo-func and bar-func are functions:
foo-func: func [ a b ] [ print "foo" ]
bar-func: func [ a b ] [ print "bar" ]
The idea is to select the function starting from the string, so:
f: select handlers "foo"
so that executing f is the same as executing foo-func and then call f with some arguments:
f param1 param2
I tried quoting the words in the map!, or using get-words but without success.
Using a get-word! at the console, without passing through a map! it works:
>> a: func [] [ print "Hello world!" ]
>> a
Hello world!
>> b: :a
>> b
Hello world!
Any help appreciated.
select handlers "foo" only get the word foo-func:
f: select handlers "foo"
probe f ;will get: foo-func
You need to get its content:
f: get f
f 1 2 ;will print "foo"
Or more compact:
f: get select handlers "foo"
It's better to actually have the reference to the function in the map, rather than a word that refers to the function. If you store a word then you have to make sure the word is bound to an object which has a reference to that function, like this:
handlers: object [
foo-func: func [ a b ] [ print "foo" ]
bar-func: func [ a b ] [ print "bar" ]
]
handler-names: map [
"foo" foo-func
"bar" bar-func
]
apply get in handlers select handler-names name args
But if you just have a reference to the function in your map, you don't have to do the double indirect, and your code looks like this:
handlers: map reduce [
"foo" func [ a b ] [ print "foo" ]
"bar" func [ a b ] [ print "bar" ]
]
apply select handlers name args
Cleaner code, and more efficient too. Or if you're careful enough, like this:
handlers/(name) a b
The path method above will also work if you want the code to do nothing if there is no handler - common in cases where you have optional handlers, such as in GUIs.
You can even have more than one reference to the same function with different key names. You don't have to assign functions to words, they're just values. You can also use the path method to collect the handlers in the first place, saving a reduce.
handlers: make map! 10 ; preallocate as many entries as you expect
handlers/("foo"): func [ a b ] [ print "foo" ]
handlers/("bar"): func [ a b ] [ print "bar" ]
handlers/("baz"): select handlers "bar" ; multiple references
That path syntax is just another way to call poke, but some prefer it. We have to put the string values in parens because of a (hopefully temporary) syntax conflict, but within those parens the string keys work. It's a faster alternative to do select or poke.
foo-func in your map is just an unevaluated word
>> type? select handlers "foo"
== word!
You should first create your functions and then reduce the block, you use for creating your handler map so
handlers: make map! reduce [
"foo" :foo-func
"bar" :bar-func
]
then you have functions inside your map
>> type? select handlers "foo"
== function!
Try:
....
f: do select handlers "foo"
....
Related
New to Karate, and JSON, for that matter, but I've got a variable like:
response {
entries {
products [
{
names [
"Peter Parker",
"Tony Stark",
"Captain America"
]
},
{
names [
"Thomas Tinker",
"Jimmy Johnson",
"Mama Martha"
]
}
]
}
}
match each response.entries.products[*].names returns a list like:
["Peter Parker","Tony Stark","Captain America","Thomas Tinker","Jimmy Johnson","Mama Martha"]
But I'd like to assign that output to a variable, such as:
* def variable = response.entries.products[*].names
that would hold a similar value. When I use the above line, I get the following error:
Expected an operand but found *
Is it possible to achieve that, or something similar? If so, how?
Thanks!
Yes, there is syntax for that:
* def variable = $response.entries.products[*].names
Read the docs: https://github.com/intuit/karate#get
I am using Karate API framework for the API automation and came across with one scenario, the scenario is when I am hitting a post call it gives me some json response and few of the items are having tags whereas few of them are showing tags as blank to get all the tags below is the feature file scenario line
* def getTags = get response.items[*].resource.tags
It is giving me response as
[
[
],
[
],
[
{
"tags" : "Entertainment"
}
],
[
],
[
{
"tags" : "Family"
}
],
As you can see out of 5 or 6 tags only 2 tags are having the value, so I want to capture if any tags value is showing or not. What would be the logic for the assertion considering these tags can all come as empty and sometimes with come with a string value. In above case "Family" & "Entertainment"
Thanks in advance !
* match each response.items[*].resource.tags == "##string"
This will validate that tags either doesn't exist or is a string.
I think you can use a second variable to strip out the empties, or maybe your original JsonPath should use .., you can experiment:
* def allowed = ['Music', 'Entertainment', 'Documentaries', 'Family']
* def response =
"""
[
[
],
[
],
[
{
"tags":"Entertainment"
}
],
[
],
[
{
"tags":"Family"
}
]
]
"""
* def temp = get response..tags
* print temp
* match each temp == "#? allowed.contains(_)"
I applied the GREL expression "value.split(/a/)" to some cells:
abcdef -> [ "", "bcdef" ]
bcdefa -> [ "bcdef" ]
badef -> [ "b", "def" ]
I can't understand why the first cell gives me a "" element in the resulting table. Is it a bug?
Thanks!
I don't know Java enough to comment on the source code for this function, but according to one of the developers of Open Refine this behavior is normal (edit : More details in Owen's comment, below). This is why there are other functions to split a string.
value.smartSplit(/a/), for example, gives a more consistent result when sep is at the begining or at the end of the string:
row value value.smartSplit(/a/)
1. abcdef [ "", "bcdef" ]
2. bcdefa [ "bcdef", "" ]
3. badef [ "b", "def" ]
This is the same result as using partition() with the omitfragment = true option enabled:
row value value.partition(/a/, true)
1. abcdef [ "", "bcdef" ]
2. bcdefa [ "bcdef", "" ]
3. badef [ "b", "def" ]
This works:
>> Oblock: [FirstName: ""
[ LastName: ""
[ BirthDate: ""]
== [FirstName: ""
LastName: ""
BirthDate: ""
]
>> Person: Make Object! OBlock
>> Person
>> probe Person
make object! [
FirstName: ""
LastName: ""
BirthDate: ""
]
>> Person/FirstName
== ""
>> Person/FirstName: "John"
== "John"
But this doesn't work
>> List: ["Id" "FirstName" "LastName"]
== ["Id" "FirstName" "LastName"]
>> Person: []
== []
>> foreach attribute List [
[ Append Person to-word rejoin [attribute {: ""}]
[ ]
== [Id: "" FirstName: "" LastName: ""]
>> Person/FirstName
** Script Error: Invalid path value: FirstName
** Where: halt-view
** Near: Person/FirstName
>>
Why ?
There are so many ways to do this, but here's one way that adheres closely to the way you seem to envision it:
list: [ "Id" "FirstName" "LastName" ]
person: []
forall list [
repend person [to-set-word first list ""]
]
person: make object! person
print person/FirstName
; == ""
In a traditional programming language, you do something like this to set the value of a variable:
x = 3;
In REBOL, you do this:
x: 3
In a traditional programming language, = is an operator, but : is not an operator in REBOL. It is a part of the word itself. This is a very important distinction, and it's why what you tried to do above did not work. x: is a set-word!, and to make one from a string you have to use to-set-word.
to-set-word "x"
; == x:
Also, you seem to be confusing objects and blocks. This is an object:
person: make object! [ first-name: "Jasmine" last-name: "Byrne" ]
This is a block:
person: [ first-name "Jasmine" last-name "Byrne" ]
They are not the same.
The reboltutorial's "person" block looks like exactly same in appearence with Geogory's.
But in fact person/1(the block) is "id: " in the first post witch type is a string!, id is just only part of it.
in second post, person/1 is "id:", witch type is set-word!.
This is the essential difference of them.
Why do I have to cast typeof to string with switch to make it work ?
This doesn't work:
typeof: type? get 'optional
switch typeof [
word! [
print "word"
]
string! [
print "string"
]
]
This works:
typeof: type? get 'optional
switch to-string typeof [
"word" [
print "word"
]
"string" [
print "string"
]
]
switch type?/word :optional [
word! [ print "word" ]
string! [ print "string" ]
]
OR
switch type? :optional reduce [
word! [ print "word" ]
string! [ print "string" ]
]
The reason is that the REBOL doesn't reduce ("evaluate") the cases in the switch statement. Without the /word refinement, the type? function returns a datatype!, but the switch statement tries to match this against a word!, and it fails.
I realize this might be confusing, so your best bet is either to convert the type to a string (as you did), or use one of the two idioms I've suggested. I prefer the first one, using type?/word.