Converting Tcl to C++

Question

I am trying to convert some tcl script into a C++ program. I don't have much experience with tcl and am hoping someone could explain what some of the following things are actually doing in the tcl script:

    1) set rtn [true_test_sfm $run_dir]
    2) cd [glob $run_dir]
    3) set pwd [pwd]

Is the first one just checking if true_test_sfm directory exists in run_dir?

Also, I am programming on a windows machine. Would the system function be the equivalent to exec statements in tcl? And if so how would I print the result of the system function call to stdout?

Answer 1

In Tcl, square brackets indicate "evaluate the code between the square brackets". The result of that evaluation is substituted for the entire square-bracketed expression. So, the first line invokes the function true_test_sfm with a single argument $run_dir; the result of that function call is then assigned to the variable rtn. Unfortunately, true_test_sfm is not a built-in Tcl function, which means it's user-defined, which means there's no way we can tell you what the effect of that function call will be based on the information you've provided here.

glob is a built-in Tcl function which takes a file pattern as an argument and then lists files that match that pattern. For example, if a directory contains files "foo", "bar" and "baz", glob b* would return a list of two files, "bar" and "baz". Therefore the second line is looking for any files that match the pattern given by $run_dir, then using the cd command (another Tcl built-in) to change to the directory found by glob. Probably $run_dir is not actually a file pattern, but an explicit file name (ie, no globbing characters like * or ? in the string), otherwise this code may break unexpectedly. On Windows, some combination of FindFirstFile/FindNextFile in C++ could be used as a substitute for glob in Tcl, and SetCurrentDirectory could substitute for cd.

pwd is another built-in Tcl function which returns the process current working directory as an absolute path. So the last line is querying the current working directory and saving the result in a variable named pwd. Here you could use GetCurrentDirectory as a substitute for pwd.