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Many functions return useful values whether or not the function has side effects. In most cases, this value is used to signify signifies whether the function successfully completed its task or if some error occurred. Other times, the value is the result of some computation and is an integral part of the function's API.

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my $source;
open(SOURCEmy $SOURCE, "<", $source);
@lines = (<SOURCE><$SOURCE>);
close(SOURCE$SOURCE);

It makes sure the variable containing the file name is properly defined, but it does nothing else to catch errors. Consequently, any error, such as the file not existing, being unreadable, or containing too much data to read into memory, will cause the program to abort.

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my $source;
open(SOURCEmy $SOURCE, "<", $source) or croak "error opening $source: $!";
@lines = (<SOURCE><$SOURCE>);
close(SOURCE$SOURCE) or croak "error closing $source: $!";

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use autodie;

my $source;
open(SOURCEmy $SOURCE, "<", $source);
@lines = (<SOURCE><$SOURCE>);
close(SOURCE$SOURCE);

EXP32:EX2: Functions that send data to standard output or standard error need not have their return values checked. This includes print and printf, but only if their filehandle file handle argument is not supplied or is explicitly set to *STDOUT or *STDERR. If they send their output to any other filehandlefile handle, their return value must be checked.

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Failure to handle error codes or other values returned by functions can lead to incorrect program flow and violations of data integrity.

Automated Detection

Related Guidelines

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Bibliography

FIO30-PL. Do not use the two-argument form of open()      02. Expressions      Image Added Image Added Image Modified