I read a tutorial of photoshop scripting,
and I can't understand this line.
//get action ID
cTID = function(s) { return app.charIDToTypeID(s); };
sTID = function(s) { return app.stringIDToTypeID(s); };
I think these codes are call Photoshop actions,
but I don't have any references, so
I can't really understand how to use these.
Why are they need and How to use these?
Well, the code you posted creates convenient aliases for the charIDToTypeID and stringIDToTypeID functions. Those functions simply convert strings to an enumeration value of type PSConstants. For instance,
CharIDToTypeID("BD1") //returns 1111765280 which corresponds to PSConstants.phEnumBitDepth1
See http://www.pcpix.com/Photoshop/
Related
Is using a variable from outside an observable within an operator considered a (significantly) bad practice?
createObservableExample1(parameter1: string, obs$: Observable<string>): Observable<string> {
return obs$.pipe(
map( x => {
const returnValue = `${parameter1}, ${x}`;
return returnValue;
})
);
}
I understand you can do something like this:
createObservableExample2(parameter1: string, obs$: Observable<string>): Observable<string> {
return combineLatest([
of(parameter1),
obs$
]).pipe(
map( (x, y) => {
const returnValue = `${x}, ${y}`;
return returnValue;
})
);
}
But is it worth it?
Does this just come down to accessing variables from outside the scope of anonymous function? Would this force the context of the enclosing method to exist for longer than it should? I remember a code tool I used to use for C# complaining about something similar to this. I have found somewhat related topics by searching for, "anonymous functions and closures", but as of yet, nothing really discussing the scenario explained above.
I ask because I have been creating some relatively complex observables that have enormous operator chains, and constantly adding the needed variables, using combineLatest and of, from the parent scope can make the code even harder to follow.
When I teach Reactive programming to neophytes, I try to make them grasp : Do not break the reactivity by having uneccessary side effects :
no input that from a state (for example using a class or instance property
no storing outside value.
There is none of these red flags in your example. Your function is pure & idempotent with both implementation, go with what ever you like and if possible be consistant within your code base !
I currently have two macros that are part of a (very limited-audience) plugin I'm developing, that both look basically like:
(function(){
exports.name = "name";
exports.params = [
{name: "value"}
];
function get(tiddler) {
// return some contents of some tiddler fields according to some rule
}
function parse(data) {
// convert string to some kind of useful object
}
function logic(x, y) {
// determine whether the two objects correspond in some way
};
function format(data, title) {
// produce WikiText for a link with some additional decoration
};
exports.run = function(value) {
value = parse(value);
var result = [];
this.wiki.each(function(tiddler, title) {
var data = get(tiddler);
if (data !== undefined && logic(value, parse(data))) {
result.push(format(data, title));
}
});
return result.join(" | ");
};
})();
So they're already fairly neatly factored when considered individually; the problem is that only the core logic is really different between the two macros. How can I share the functions get, logic and format between the macros? I tried just putting them in a separate tiddler, but that doesn't work; when the macros run, TW raises an error claiming that the functions are "not defined". Wrapping each function as its own javascript macro in a separate tiddler, e.g.
(function(){
exports.name = "get";
exports.params = [
{name: "tiddler"}
];
exports.run = function(tiddler) {
// return some contents of some tiddler fields according to some rule
}
})();
also didn't help.
I'd also like to set this up to be more modular/flexible, by turning the main get/parse/logic/format process into a custom filter, then letting a normal filter expression take care of the iteration and using e.g. the widget or <> macro to display the items. How exactly do I set this up? The documentation tells me
If the provided filter operators are not enough, a developer can add
new filters by adding a module with the filteroperator type
but I can't find any documentation of the API for this, nor any examples.
How can I share the functions get, logic and format between the macros?
You can use the Common/JS standard require('<tiddler title>') syntax to access the exports of another tiddler. The target tiddler should be set up as a JS module (ie, the type field set to application/javascript and the module-type field set to library). You can see an example here:
https://github.com/Jermolene/TiddlyWiki5/blob/master/core/modules/widgets/count.js#L15
I'd also like to set this up to be more modular/flexible, by turning the main get/parse/logic/format process into a custom filter, then letting a normal filter expression take care of the iteration and using e.g. the widget or <> macro to display the items. How exactly do I set this up?
The API for writing filter operators isn't currently documented, but there are many examples to look at:
https://github.com/Jermolene/TiddlyWiki5/tree/master/core/modules/filters
Is there any way you can make "document.getElementById" into a variable?
I want to be able to write
myVariable("id").innerHTML = (blabla);
instead of
document.getElementById("id").innerHTML = (blabla);
Pardon me if this has been answered. I've sought and found nil! newbie
You can wrap the output into another function
var shortID = function(id) {
return document.getElementById(id);
}
shortID('myID').innerHTML = "...";
To provide a simpler way to call common code, you can just define your own function like migvill suggests.
To answer the question directly though, you can point to the document.getElementById function (or any other function) using a variable. This is as obvious as you could imagine:
var myVariable = document.getElementById;
The problem with this is that the function itself (the object that myVariable now points to) is not intrinsically linked to the document object that it is designed to work with. When you write document.getElementById("id"), the document is automatically given to the function, but with myVariable you would need to specify it. This can be done using the call function:
myVariable.call(document, "id").innerHTML = "blabla";
And finally, the bind function can be used to create a new function that automatically links the given object (this has essentially the same effect as defining your own wrapper function):
var newFunc = myVariable.bind(document);
newFunc("id").innerHTML = "blabla";
I am trying to figure why my ajax $each alters the way my list of names gets printed?
I have an json string like this:
[{"name":"Adam","len":1,"cid":2},{"name":"Bo","len":1,"cid":1},{"name":"Bob","len":1,"cid":3},{"name":"Chris","len":1,"cid":7},{"name":"James","len":1,"cid":5},{"name":"Michael","len":1,"cid":6},{"name":"Nick","len":1,"cid":4},{"name":"OJ","len":1,"cid":8}]
Here all the names are sorted in alphabetic order, but when getting them out they are sorted by "cid"? Why, and how can I change this?
Here is my jQuery:
var names = {};
$.getJSON('http://mypage.com/json/names.php', function(data){
$.each(data.courses, function (k, vali) {
names[vali.cid] = vali.name;
});
});
I guess its because "names[vali.cid]", but I need that part to stay that way. Can it still be done?
Hoping for help and thanks in advance :-.)
Ordering inside an object is not really defined or predictable when you iterate over it. I would suggest sorting the array based on an internal property:
var names = [];
$.getJSON('http://mypage.com/json/names.php', function(data){
$.each(data.courses, function (k, vali) {
names.push({name: vali.name, cid: vali.cid});
});
names.sort(function(a, b) {
return a.name.localeCompare(b.name);
});
});
Now you have an array that is ordered and you can iterate over it in a predictable order as well.
There is no "ajax $each" - you probably mean the jQuery function.
With "when getting them out" I presume you mean something like console.debug(names) after your $each call
Objects aren't ordered in javascript per definition, so there is no more order in your variable "names". Still, most javascript implementations today (and all the ones probably important to you - the ones used in the most used browsers) employ a stable order in objects which normally depends on the order you insert stuff.
All this said, there can probably be 3 reasons you're not getting what you're expecting:
Try console.debug(data) and see what you get - the order as you want it?
As you don't explicitly state how you debug your stuff, the problem could be in the way you output and not the data is stored. Here too try console.debug(names).
You're using a function which dereferences on expection, like console.*. This means if you console.debug() an object, the displayed values will depend on the moment you unfold the displayed tree in your browser, not when the line was called!
I've seen classes where constants are passed to methods, I guess its done to define some kind of setting in that function. I cant find it anywhere now to try to find out the logic, so I though I could ask here. How and why do you use this concept and where can I find more information about it?
The example below is written in PHP, but any language that handles constants would do I guess..
// Declaring class
class ExampleClass{
const EXAMPLE_CONST_1 = 0;
const EXAMPLE_CONST_2 = 1;
function example_method($constant(?)){
if($constant == ExampleClass::EXAMPLE_CONST_1)
// do this
else if($constant == ExampleClass::EXAMPLE_CONST_2)
// do that
}
}
// Using class
$inst = new ExampleClass();
$inst->example_method(ExampleClass::EXAMPLE_CONST_1);
To me its more clear to pass "ExampleClass::EXAMPLE_CONST_1" than to just pass "1", but it's that the only reason to pass constant?
Simply passing 1 doesn't say much. By having a constant you can have a description about the settings in the name.
example:
constant RAIN = 1;
method setWeather(RAIN);
Atleast that's how and why I use it.
It is always a good idea to avoid literals being passed around. By assigning a name, anyone reading your code has a chance to understand what that value means - a number has no meaning. It might also help you maintaining your code: If for some requirement the value has to be changed, you can easily do it in one place, instead of checking each and every value occurrence.