Passing indented code to compile()

[Harvey Thomas]

John Wilson wrote:
> 
> I hit a problem when trying to compile some Python code 
> embedded in an XML
> document.
> 
> For example:
> 
>         <execute globals="globals" locals="locals">
>             print "hello"
>         </execute>
> 
> If I just pass the string I construct from the SAX callbacks 
> the compile
> function complains of a syntax error.
> 
> There seem to be two problems here:
> 
> 1/ The line '            print "hello"' is preceded by a 
> blank line and
> followed by some whitespace.
> 
> 2/  The line '            print "hello"' starts with whitespace.
> 
> I can fix point 1/ trivially by can remove leading and 
> trailing blank lines.
> 
> Point 2/ is harder to fix. It isn't simple to shift an 
> arbitrary block of
> Python code to the left (comments and triple-quoted strings 
> spring to mind
> as sources of complexity).
> 
> What I do is to remove the leading and trailing blank lines, 
> check to see if
> the first character of the remaining lines (if any) is 
> whitespace. If it is
> then I prepend the statement "if 1:". I then append a blank 
> line to the
> resulting code block.
> 
> Questions:
> 
> 1/ Will this always work?
> 
> 2/ Is there a better way of doing this?
> 
> John Wilson
> The Wilson Partnership
> http://www.wilson.co.uk
> 
Assuming that you are parsing for well-formed XML, then all white space is considered significant; hence the blank line and leading white space before/after the print statement. If the XML document had contained

<execute globals="globals" locals="locals">print "hello"</execute>

then you wouldn't have had the problem. If the code to be compiled spans more than one line I can see further problems though as Python's indentation rules are going to get in the way unless the XML is very carefully formatted.

HTH

Harvey

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