UDF called in cmd syntax + force expr + object = ByRef?? Topic is solved

[Coco]

Are objects passed to functions called in command syntax treated as ByRef? See sample below:

Code: Select all

obj := ["Hello World"] ;// store in variable
test % obj ;// works
test % obj := ["Hello World"] ;// works
test % ["Hello World"] ;// does not work

test(arg) { ;// arg is not ByRef
	MsgBox % IsObject(arg)
	MsgBox % arg[1]
}

[lexikos]

Command syntax doesn't support objects. Each arg evaluates to a string or variable reference. % obj evaluates to a variable reference, so after all args are evaluated and the function call is being made, the variable's contents are copied into the arg parameter. % ["Hello World"] evaluates to an empty string.

Objects are always passed by reference, if at all. You don't store an object in a variable; you store a reference to an object. ByRef has nothing to do with objects, just variables. IsByRef(arg) returns false and assigning arg := 1 does not affect obj.

[joedf]

As per documentation, this should suffice to free an object : obj := ""
But, is this always true? Would it better to do this? Object.SetCapacity(0)
Or with variables in general?
var := "" vs VarSetCapacity(var,0)
It seems to be the same...?

[just me]

Object.SetCapacity(0)
MaxItems: The maximum number of key-value pairs the object should be able to contain before it must be automatically expanded. If less than the current number of key-value pairs, the object is shrunk to fit.

[joedf]

I read that... So what about?
Object.SetCapacity(0) vs obj := ""

[fincs]

obj := "" releases your reference to the object (which is unnecessary 99% of the time). If there are no more references left to the object, it is deleted; whereas obj.SetCapacity(0) wipes an object's contents; but does not free it completely.

[lexikos]

joedf, I can't see in what way your query is related to the topic of this thread.

(which is unnecessary 99% of the time).

That seems like the wrong point to make. If the "99% of the time" only covers moments that you don't want the object to be freed, or cases where the variable is local and will be freed automatically, then sure. It is absolutely necessary to do obj := "" (or something equivalent) if the variable isn't going to be freed by some other means.

obj.SetCapacity(0) wipes an object's contents; but does not free it completely.

It looks like you did not read and understand the quoted documentation either.

SetCapacity(0) does not free the object nor wipe its contents. "Shrunk to fit" means that excess unused space is reclaimed by reallocating an internal array. All contents are preserved and the end result is an object whose capacity is equal to the number of key-value pairs it contains.

[guest3456]

perhaps the docs can be updated to display this also:

SetCapacity(0) does not free the object nor wipe its contents. "Shrunk to fit" means that excess unused space is reclaimed by reallocating an internal array. All contents are preserved and the end result is an object whose capacity is equal to the number of key-value pairs it contains.

[Coco]

Command syntax doesn't support objects.

Objects are always passed by reference

Thanks for clarifying. Are there plans to support objects for command syntax?

[joedf]

I see... Thank you. Sorry if was a little offtopic.. :S

[lexikos]

guest3456: I was going for brevity. Does anyone think "shrunk to fit" actually meant removing everything from the object? That doesn't make sense.

Coco: Eventually, yes.

[just me]

As a compromise:

... If less than the current number of key-value pairs, the object is shrunk to fit the current number.

Does it make sense?

[guest3456]

guest3456: I was going for brevity. Does anyone think "shrunk to fit" actually meant removing everything from the object? That doesn't make sense.

Whatever your intent, two separate users misunderstood. Clarity > Brevity imo. Pretty much whenever people have misunderstandings reading the docs, that is a time to improve the docs. This is for everyone's benefit, including yours. Less questions in the forum asking for your clarification

I do this constantly with my users. I don't have the patience to keep answering easy questions. So whenever someone misunderstands my docs, I update my docs and add more information so that the next user won't need to ask me.

Chris was fairly verbose in the original AHK docs and I think that was a good thing

[lexikos]

That's all beside the point. Did they misunderstand the documentation, or did they just make bad assumptions about what the method does without actually reading the documentation? It's completely pointless to cater the documentation to people that don't read it. In any case, I've updated it.

[lexikos]

Command syntax doesn't support objects.

I take it back. As of v2.0-a049, Coco's code works.

[joedf]

don't feed the troll!