Leaning Stoop

In computer programming, leaning toothpick syndrome (LTS) is the situation in which a quoted expression becomes visually confusing because it contains a large number of escape characters to avoid delimiter collision (i.e., to avoid ambiguous, non-deterministic interpretations in the program). Escape characters are usually backslashes (\), but can be other character types as well. An example of LTS would be /^\\\/\\+\/\\?\/\\$/. Leaning Toothpick Syndrome is named as such due to the visual appearance of each backslash (or forward slash, another common escape character) resembling a leaning toothpick, combined with LTS-suffering strings containing a large number of the tilted slashes. LTS appears in many programming languages and in many situations, including in patterns that match Uniform Resource Identifiers (URIs), programs that manipulate files and their contents, and programs that output quoted text (i.e., text that either contains quote characters, is surrounded by quote characters, or both). Many quines fall into the latter category. The official Perl documentation introduced the term to wider usage; there, the phrase is used to describe regular expressions that match Unix-style paths, in which the elements are separated by slashes /. The slash is also used as the default regular expression delimiter; so to be used literally in the expression, it must be escaped with a backslash \, leading to frequent escaped slashes represented as \/. If doubled, as in URLs, this yields \/\/ for an escaped //. A similar phenomenon occurs for MS-DOS and Windows paths, where the backslash is used as a path separator, such as in C:\Users\Amy\Desktop\Q1-report.pdf, rather than a Unix-style /home/Amy/Desktop/Q1-report.pdf with forward slashes. As a result of using \ for paths instead of /, Windows typically requires extra escape characters when compared to Unix-style paths. Therefore, Windows paths are more likely to cause frustration to programmers.