[news.eclipse.technology.dltk] Re: ExtendedVariableReference and CallHol

[Alex Panchenko <alex@xxxxxxxxx>]

Hi Chuck,

CallExpression is part of the dltk.core, but ExtendedVariableReference 
and CallHolder are specific to the python.

The framework declare base classes for the AST to allow core support for 
common functionality - search, outline, call & type hierarchies, etc.

In case of the CallExpression the implicit "this" parameter is usually 
stored as null to the receiver. In scripting languages it is usually 
impossible to distinguish instance vs static methods during parsing 
phase, so it is implemented that way.

For example, the expression

print("hello")

will have:

receiver=null
name=SimpleReference("print")
args=[StringLiteral("hello")]

and the expression

output.print("hello")

will be

receiver=VariableReference("output")
name=SimpleReference("print")
args=[StringLiteral("hello")]

The receiver is declared as ASTNode because it is the base case in the 
hierarchy. The situation with Statement/Expression is complex because 
various languages have different notions of what an 'expression' and a 
'statement' are. Probably we will merge this classes in the future. The 
ASTNode is the most general case. The future of the AST class hierarchy 
is often discussed, so this is not the "final" solution, it can (and 
most probably will) be changed at some time.

Regards,
Alex


Chuck Doucette wrote:
> Also, if I do try to use CallExpression instead of CallHolder (which only 
> holds the arguments),
> what is the receiver - is it the object that you are operating on, i.e. 
> this, whose type defines the method? In CallExpression, it is an ASTNode. I 
> would have thought it would be an expression instead.
>
> Chuck
>
> "Chuck Doucette" <cdoucette@xxxxxxxxxxx> wrote in message 
> news:g3bc5r$u8c$1@xxxxxxxxxxxxxxxxxxxx
> > Your full sample editor uses ExtendedVariableReference and CallHolder,
> > but other internal code appears to use CallExpression and 
> > MethodCallExpression instead.
> > Should I switch my code to be using CallExpression/MethodCallExpression 
> > instead?
> >
> > Chuck