[SOLVED]VEX Concat File Path and File Name?

[Atom]

Hi All,

 

I am trying to construct an attribute that is a filename. However, as with many languages there is a problem with BACK\SLASHES in a string. I have tried double slashing to resolve the issue but it seems to have no effect. I always get a mangled string as my filename when I review it in the Geometry Spreadsheet.

 

How do define a file path string in VEX so I can properly store it as an attribute in the spreadsheet?

s@element_name = "";
string full_path = "";
string path_to_maps ="C:\\Users\\Developer\\Documents\\Maps\\cc0_Lens Flare Rig Elements";
string element_names[] = {"Star3.png","Star4.png","Star5.png"};
for(int i=0; i< @numpt; i++) {
    //full_path = sprintf("%s%s", path_to_maps,element_names[i]);
    full_path = concat(path_to_maps,element_names[i]);
    setpointattrib(geoself(), "element_name", i, full_path, "set");
    full_path = "";
}

Edited November 8, 2015 by Atom

[fsimerey]

I found this :

string path_to_maps ='C:\\\\\\Users\\\\\Developer\\\\\Documents\\\\\Maps\\\\\cc0_Lens Flare Rig Elements';

[loopyllama]

I haven't tried, but wouldn't a single forward slash work?

s@path = "C:/mySecretMaps/pirateTreasure"; 

[f1480187]

Your escape sequences are valid in .vfl or other normal VEX sources. Code field is a string parameter being expanded as normal expression. It also seems that for Snippet and Wrangle nodes it expanded twice (using HScript rules), with additional expansion between evaluated code field and VEX code generation. So, in Point Wrangle you need to use eight backslashes to get your escape sequence correct in generated VEX code: \\\\\\\\ > \\\\ > \\. To get two resulting backslashes in string you need to use sixteen \\\\\\\\\\\\\\\\ > \\\\\\\\ > \\\\. You can use lesser, actually 5 and 13, because leading \\\ in HScript expanding into \\ and, again, doing it twice for Snippet and Wrangle: \\\\\ > \\\ > \\ and \\\\\\\\\\\\\ > \\\\\\\ > \\\\. But I suggest to use "scalable" tactic. Inline VOP correctly expands it's string once, so, use four to get one and eight to get two. And SESI may fix it someday for Wrangle and Snippet also.

 

In docs for Python's Regexes it is called Backslash Plague, and solution is using raw strings. VEX's Regexes was introduced in H14 as well as python-style raw strings syntax. In theory, you can use raw strings, but it still working correct only inside direct VEX source. With an interesting exception for single backslash, you still need to flood backslashes in code fields.

# Original parameter:
 "test\\\\\\\\test"
 "test\\\\\\\\\\\\\\\\test"
r"test\test"
r"test\\\\\\\\test"

# Expanded parameter:
 "test\\\\test"
 "test\\\\\\\\test"
r"test\test"
r"test\\\\test"

# Generated VEX Code:
 "test\\test"
 "test\\\\test"
r"test\test"
r"test\\test"

# Resulting string:
test\test
test\\test
test\test
test\\test

[Atom]

Thanks for the explanation.

 

And yes, Francois, reversing the back slash to a forward slash did work for me on Windows.

Edited November 8, 2015 by Atom