jython-dev

[Jython-dev] python interpreter and conditional statements

[J D <jam...@ho...>]

Hi, perhaps you can help.  As a python and jython newbie I am trying to 
embed some jython code into my java program.  Seems an easy way to do this 
is by creating a PythonInterpreter object.  So far, so good.  My problem 
arises when I attempt a conditional statement such as:

String erpFormula = ( "if ( 10 * math.log10( TransmitPower ) > 10 and 
LineLoss + RadomeLoss > 6 ): resultant = 20; else: resultant = 10" );

PythonInterpreter interp = new PythonInterpreter();
interp.exec( erpFormula );

The runtime error is: Syntax error: invalid syntax. Evidentally it chokes on 
the else keyword.

If I remove the else..., it runs correctly.

Any and all help you can provide is much appreciated, Jim.


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Re: [Jython-dev] python interpreter and conditional statements

[Titus B. <ti...@ca...>]

-> Hi, perhaps you can help.  As a python and jython newbie I am trying to 
-> embed some jython code into my java program.  Seems an easy way to do this 
-> is by creating a PythonInterpreter object.  So far, so good.  My problem 
-> arises when I attempt a conditional statement such as:
-> 
-> String erpFormula = ( "if ( 10 * math.log10( TransmitPower ) > 10 and 
-> LineLoss + RadomeLoss > 6 ): resultant = 20; else: resultant = 10" );
-> 
-> PythonInterpreter interp = new PythonInterpreter();
-> interp.exec( erpFormula );
-> 
-> The runtime error is: Syntax error: invalid syntax. Evidentally it chokes on 
-> the else keyword.
-> 
-> If I remove the else..., it runs correctly.

The above statement isn't valid in (C)Python, either; I'd suggest you create
a multiline string.  I'm not sure how to fit the 'else' statement in on the
end of a single line...

--titus

Re: [Python-Help] Re: [Jython-dev] python interpreter and conditional statements

[Alex M. <al...@al...>]

On Monday 24 September 2001 23:49, Titus Brown wrote:
	...
> -> String erpFormula = ( "if ( 10 * math.log10( TransmitPower ) > 10 and
> -> LineLoss + RadomeLoss > 6 ): resultant = 20; else: resultant = 10" );
> ->
> -> PythonInterpreter interp = new PythonInterpreter();
> -> interp.exec( erpFormula );
> ->
> -> The runtime error is: Syntax error: invalid syntax. Evidentally it
> chokes on -> the else keyword.
> ->
> -> If I remove the else..., it runs correctly.
>
> The above statement isn't valid in (C)Python, either; I'd suggest you
> create a multiline string.  I'm not sure how to fit the 'else' statement in
> on the end of a single line...

There is no way to fit an if AND its else on a single line.  You are fully
correct that newline characters (and indentation) should be inserted
instead:

String erpFormula = ( "if ( 10 * math.log10( TransmitPower ) > 10 and
  LineLoss + RadomeLoss > 6 ):\n  resultant = 20\nelse:\n  resultant = 10\n" 
);


Alex