declare a scalar variable to be of type "string", or of type "number", or
type "filehandle", or anything else. Perl is a contextually polymorphic
language whose scalars can be strings, numbers, or references (which
-includes objects). While strings and numbers are considered the pretty
+includes objects). While strings and numbers are considered pretty
much same thing for nearly all purposes, references are strongly-typed
uncastable pointers with built-in reference-counting and destructor
invocation.
scalar(@whatever) == $#whatever + 1;
-Some programmer choose to use an explcit conversion so nothing's
+Some programmers choose to use an explicit conversion so nothing's
left to doubt:
$element_count = scalar(@whatever);
quoting. An unquoted identifier works like double quotes. There must
be no space between the C<E<lt>E<lt>> and the identifier. (If you put a space it
will be treated as a null identifier, which is valid, and matches the
-first blank line--see the Merry Christmas example below.) The terminating
-string must appear by itself (unquoted and with no surrounding
-whitespace) on the terminating line.
+first blank line.) The terminating string must appear by itself
+(unquoted and with no surrounding whitespace) on the terminating line.
print <<EOF;
The price is $Price.
I said bar.
bar
- myfunc(<<"THIS", 23, <<'THAT'');
+ myfunc(<<"THIS", 23, <<'THAT');
Here's a line
or two.
THIS
Let the objects look after themselves! Generally, avoid hardwired
class names as far as possible.
-Avoid $r->Class::func() where using @ISA=qw(... Class ...) and
-$r->func() would work (see perlbot man page for more details).
+Avoid $r-E<gt>Class::func() where using @ISA=qw(... Class ...) and
+$r-E<gt>func() would work (see perlbot man page for more details).
Use autosplit so little used or newly added functions won't be a
burden to programs which don't use them. Add test functions to
$no_caps_here function scope my() or local() variables
Function and method names seem to work best as all lowercase.
-E.g., $obj->as_string().
+E.g., $obj-E<gt>as_string().
You can use a leading underscore to indicate that a variable or
function should not be used outside the package that defined it.
short or common names to reduce the risk of name clashes.
Generally anything not exported is still accessible from outside the
-module using the ModuleName::item_name (or $blessed_ref->method)
+module using the ModuleName::item_name (or $blessed_ref-E<gt>method)
syntax. By convention you can use a leading underscore on names to
informally indicate that they are 'internal' and not for public use.
return $self;
}
-Or if you expect people to call not just C<CLASS->new()> but also
-C<$obj->new()>, then use something like this. The initialize()
+Or if you expect people to call not just C<CLASS-E<gt>new()> but also
+C<$obj-E<gt>new()>, then use something like this. The initialize()
method used will be of whatever $class we blessed the
object into:
display {find Critter "Fred"} 'Height', 'Weight';
-For C++ fans, there's also a syntax using -> notation that does exactly
+For C++ fans, there's also a syntax using -E<gt> notation that does exactly
the same thing. The parentheses are required if there are any arguments.
$fred = Critter->find("Fred");
An indirect object is limited to a name, a scalar variable, or a block,
because it would have to do too much lookahead otherwise, just like any
-other postfix dereference in the language. The left side of -> is not so
+other postfix dereference in the language. The left side of -E<gt> is not so
limited, because it's an infix operator, not a postfix operator.
That means that below, A and B are equivalent to each other, and C and D
@foo = @foo[$#foo-4 .. $#foo]; # slice last 5 items
The range operator (in a list context) makes use of the magical
-autoincrement algorithm if the operaands are strings. You
+autoincrement algorithm if the operands are strings. You
can say
@alphabet = ('A' .. 'Z');
element. It's easy to make a I<LARGE> data space this way, so use with
care.
-The null filehandle <> is special and can be used to emulate the
-behavior of B<sed> and B<awk>. Input from <> comes either from
+The null filehandle E<lt>E<gt> is special and can be used to emulate the
+behavior of B<sed> and B<awk>. Input from E<lt>E<gt> comes either from
standard input, or from each file listed on the command line. Here's
-how it works: the first time <> is evaluated, the @ARGV array is
+how it works: the first time E<lt>E<gt> is evaluated, the @ARGV array is
checked, and if it is null, C<$ARGV[0]> is set to "-", which when opened
gives you standard input. The @ARGV array is then processed as a list
of filenames. The loop
except that it isn't so cumbersome to say, and will actually work. It
really does shift array @ARGV and put the current filename into variable
-$ARGV. It also uses filehandle I<ARGV> internally--<> is just a synonym
+$ARGV. It also uses filehandle I<ARGV> internally--E<lt>E<gt> is just a synonym
for <ARGV>, which is magical. (The pseudo code above doesn't work
because it treats <ARGV> as non-magical.)
-You can modify @ARGV before the first <> as long as the array ends up
+You can modify @ARGV before the first E<lt>E<gt> as long as the array ends up
containing the list of filenames you really want. Line numbers (C<$.>)
continue as if the input were one big happy file. (But see example
under eof() for how to reset line numbers on each file.)
... # code for each line
}
-The <> symbol will return FALSE only once. If you call it again after
+The E<lt>E<gt> symbol will return FALSE only once. If you call it again after
this it will assume you are processing another @ARGV list, and if you
haven't set @ARGV, will input from STDIN.
because that's an indirect filehandle as explained in the previous
paragraph. In older version of Perl, programmers would insert curly
brackets to force interpretation as a filename glob: C<E<lt>${foo}E<gt>>.
-These days, it's consdired cleaner to call the internal function directly
+These days, it's considered cleaner to call the internal function directly
as C<glob($foo)>, which is probably the right way to have done it in the
first place.) Example:
projects / p5sagit/p5-mst-13.2.git / commitdiff