Subj : Re: Calling a function before it's declared
To   : Brook Monroe
From : Brendan Eich
Date : Wed Nov 24 2004 05:07 pm

Brook Monroe wrote:
> Martin Honnen wrote:
> 
>>
>>
>> Brook Monroe wrote:
>>
>>
>>> Declaration order isn't critical. Calling functions that haven't been 
>>> defined yet will work because the call resolution occurs at run-time, 
>>> not compile time.
>>
>>
>>
>> You can call a function before its declaration as program execution is 
>> defined to be a two pass execution where the first pass goes through 
>> the program and executes all function declarations and then the second 
>> pass executes the global statements (e.g function calls) in source order.
>>
> Same difference.  Although that doesn't answer the question of why 
> JS_CompileFile() (which, according to that explanation, would "execute" 
> the function declarations) doesn't allow direct function calls through 
> JS_CallFunctionName() without going through JS_EvaluateScript() first.


Because compiling in the JS API has nothing to do with executing 
("according to that explanation" mixes apples and oranges -- JS API 
rules are apples, Martin's explanation of parts of ECMA-262 section 10 
are the oranges).  That's it, there isn't anything mysterious -- but 
it's deeper than you make out above.

Consider how JS_CompileFile has no effect on the object passed as the 
second parameter.  It would actually take extra code (specifically, a 
JS_ExecuteScriptPart(...PROLOG...) call after JS_CompileFile succeeded) 
to cause the declared functions and variables to be bound in the |obj| 
parameter.

If there's a need for JS_EvaluateFile, we can add that easily, but it 
hasn't been a pressing issue in almost ten years.  Much of the reason 
has to do with Unicode vs. locale- and file-dependent character set 
encodings.

/be

.