Eval Syntax Problem

[amitkhanna]

Hi pals,

Iam trying to evaluate a simple expresstion using the eval command. But iam stuck with syntax.

string $cmd = "expression -s \"" + "if(" + $posObj1[2] + ">" + 0 + ")" + "{" + $selObj[1] + ".translateZ" + "=" + $posObj2[2] + "-" + $distNode + ".distance;\"}" + "else {" + $selObj[1] + ".translateZ" + "=" + $posObj2[2] + "+" + $distNode+".distance;\"");
eval($cmd);

if(pSphere1.translateZ>0)
{pCube1.translateZ=-5-distanceBetween2.distance;}
else
{pCube1.translateZ=-5+distanceBetween2.distance;}

is what iam trying to evaluate.... where posObj[2] is the translate.Z of object 2 If please someone can correct the syntax and also PLEASE explain whats with the \"" syntax..... Ill be really thankful &....happy

Thanks a lot guys,
ak

[joojaa]

Firstofall you dont need evel here because string attribs will be able to concatenete piror to running into command. you only ever need evel if you dont know how manty inputs you have, and iin thsi case you have a fixed amont! Reevaluate your knowlege of mel.

anyway theres a syntaxc terror

string $cmd = "expression -s \"" + "if(" + $posObj1[2] + ">" + 0 + ")" + "{" + $selObj[1] + ".translateZ" + "=" + $posObj2[2] + "-" + $distNode + ".distance;\"}" + "else {" + $selObj[1] + ".translateZ" + "=" + $posObj2[2] + "+" + $distNode+".distance;}\"");

anyway this is enough

CODE
expression -s ("if(" + $posObj1[2] + "> 0 ){\n   "
+ $selObj[1] +".translateZ ="+ $posObj2[2] +"-"+ $distNode +".distance;\n}\n"
+ "else {\n   "
+ $selObj[1] + ".translateZ" + "="+ $posObj2[2] +"+"+ $distNode+".distance;}");

NO eval needed jis jsut ecessive and slows your code down

[failure]

\ inside string is called escape character. It's used to alter the interpretation of suceeding character. For instance - if you need a " character inside string it would be impossible without it:

print( "say "foo"" );

would cause a syntax error because second quote is interpreted as the end of string marker. You need a way to tell interpreter that you want the qoute character as part of the string:

print( "say \"foo\"" );

will print:

say "foo"

[amitkhanna]

Hi failure,

Thanks a lot for explaining . That was really helpful and my command is working now. I knew it was something with the " 's and \'s that was wrong and it was.

Thanks,
AK

[joojaa]

just make sure you dont evel that! its just excesssive.

[amitkhanna]

Hey Joojaa,

well I never thought that will work, but it does.... Cool...
Thanks a lot dude.

Well you knw what you both solved my 2 problems 1. with the \" in strings and other extra eval that I was using.

Good for me,
Thanks both of you guys,

Have fun,
AK

[joojaa]

[just beacsue you dont know a string variable in advbvance does not eman you eed to eval. YOu only need to eval ifd you dont know the exact amount of switches before hand. Even then its possible to circumvent in some cases by using variables in the procstyle syntax,