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Chapter 4.  Values and Expressions

 
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Chapter 4. Values and Expressions

Data is semi-animate...sort of like programmers.
Arthur Norman

Constructing and using values ought to be trivial. After all, there are very few components of a Perl program simpler than a character string or a number or a + operator.

Unfortunately, the syntax of Perl's literal values is so rich that there are plenty of ways to mess them up. Variables can interpolate unexpectedly, or fail to interpolate at all. Character escape codes and literal numbers can mysteriously appear in the wrong base. Delimiters can be just about anything you like.

And Perl's operators are even worse. Several of them are polymorphic: silently changing their behaviour depending on the type of argument they're applied to. Others are monomorphic: silently changing their arguments to fit their behaviour. Others are just plain inefficient in some usages.

This chapter suggests some appropriate coding habits that can help you avoid the pitfalls associated with creating values and manipulating them in expressions.

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