When asked about spaces in a repository URL, my response was Spaces are the DEVIL!. The more reasonable response would be…
Spaces are difficult because they serve a dual-purpose, both as a literal character and as a delimiter. Because of that ambiguity the usage of space for anything that might be used in an automation tool, or as an identifier, is discouraged.
Yes, one can use spaces in a URL, or folder name, or source file. However when the time comes for tooling around these resources the issue of encoding and escaping comes into play. If this is a headache you wish to persue, then name your source code file
process that shopping cart.php and enjoy.