To Backtick Or Not For Opinput, Oppwf, Opname

[RickWork]

Hello,

So I'm working on some otls and am having some problems with paths.....

As a test I have the following network structure:

SphereSOP->TransforrmSOP1->TransformSOP2

For TransformSOP1 I have the tx parameter set to 2.

On the TransformSOP2 I have tried the following to extract TransformSOP1's tx value:

ch(`opinput(".", 0)`"/tx")
ch(opinput(".", 0)"/tx")
ch(`opinput(".", 0)`+ "/tx")
ch(opinput(".", 0)"+ /tx")

In the long run, I'm just trying to avoid hardcoding the full path to SOPs in my expressions because I naturally get errors when I try to make an otl. I did also try oppwf() but still at a loss when to backtick, when not to backtick, how to concatenate, etc.

Any tips is much welcome!

Cheers,

Rick

[thomas.waldinger]

try

ch("../" + opinput(".", 0)+"/tx")

works for me.

[RickWork]

try

ch("../" + opinput(".", 0)+"/tx")

works for me.

20632[/snapback]

ahh very good thanks!

[edward]

I think using opinputpath(".", 0) will also work.

[RickWork]

I think using opinputpath(".", 0) will also work.

20634[/snapback]

so backticks are not needed I see. So when would i use a backick? textport only?

[edward]

In Houdini, there are two distinct languages (I *think* mostly due to legacy reasons from PRISMS). It's sort of like:

1. "hscript, the command language": the stuff found in the help command and what you type in the textport

2. "hscript, the expression language": the stuff found in exhelp and what you type in animatible parameters

So from (1), we use backticks to access (2). That's why in the textport, you need backticks for all stuff associated with exhelp. From (2), we can use the run() expression function to access (1).

In your specific example, you were in (2) trying to access (2) and so no backticks were required.

I guess a rule of thumb then is that you use backticks when passing the result of something found in exhelp to a command found in help.

[Jason]

so backticks are not needed I see. So when would i use a backick? textport only?

20639[/snapback]

Backticks are only needed for string fields. In numerical fields putting a backtick will return 0 always (which the return value of the evaluation - useless).

I get this wrong almost every day but I remember almost every day too.

[edward]

Ah yes, I forgot about string parameters. I guess more generally, backticks are used to get into the (2) world when you're outside.

[RickWork]

Ah yes, I forgot about string parameters. I guess more generally, backticks are used to get into the (2) world when you're outside.

20643[/snapback]

Yup good info guys. I get it now. It now makes sense why my otls weren't working as I expected.

Cheers,

Rick