Make Few Assumptions

In an application, you'll often need to use variables that contain indeterminate formats. For example, an application might have several variables or properties storing directory names. When using these variables, you have to add a filename to get a full file specification. How do you know whether the path stored in the variable contains a backslash? Most applications have an AppendSlash routine that adds a backslash to a path if it doesn't have one, so you might be tempted to assume the format just because you've run it once in debug mode to check. You need to keep in mind, especially in large projects, that values of variables are often changed by other programmers, so a path that has the trailing backslash in one instance might not in another. Depending on the application, you might discover these errors immediately or not until some later time. In the case of the backslash, rather than rely on it being there, assume it could be missing and use your AppendSlash routine to check for it everywhere. You should apply this thinking whenever a particular format cannot be guaranteed.

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