Fully translated.

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Kang-min Liu 2020-05-28 23:58:53 +08:00
parent 6e2693ac6b
commit 095c07af91

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@ -94,37 +94,34 @@ my @colors = values %fruit_color;
# 關於純量、陣列、雜湊,在 perldata 文件之中,有更完整的描述。 # 關於純量、陣列、雜湊,在 perldata 文件之中,有更完整的描述。
# (perldoc perldata) # (perldoc perldata)
#### References #### 參照
# More complex data types can be constructed using references, which # 以參照能組出結構更為複雜的資料型別。像是在陣列中放入雜湊、在雜湊裡放入陣列的雜湊。
# allow you to build arrays and hashes within arrays and hashes.
my $array_ref = \@array; my $array_ref = \@array;
my $hash_ref = \%hash; my $hash_ref = \%hash;
my @array_of_arrays = (\@array1, \@array2, \@array3); my @array_of_arrays = (\@array1, \@array2, \@array3);
# You can also create anonymous arrays or hashes, returning a reference: # 匿名陣列與匿名雜湊也是參照
my $fruits = ["apple", "banana"]; my $fruits = ["apple", "banana"];
my $colors = {apple => "red", banana => "yellow"}; my $colors = {apple => "red", banana => "yellow"};
# References can be dereferenced by prefixing the appropriate sigil. # 在參照之前補上適當的印記,是為解參照。
my @fruits_array = @$fruits; my @fruits_array = @$fruits;
my %colors_hash = %$colors; my %colors_hash = %$colors;
# As a shortcut, the arrow operator can be used to dereference and # 以箭頭算符,便可在解參照同時存取其中一值。
# access a single value.
my $first = $array_ref->[0]; my $first = $array_ref->[0];
my $value = $hash_ref->{banana}; my $value = $hash_ref->{banana};
# See perlreftut and perlref for more in-depth documentation on # 欲深入了解參照,詳見 perlreftut 與 perlref 兩份文件
# references.
#### Conditional and looping constructs #### 條件結構與迴圈結構
# Perl has most of the usual conditional and looping constructs. # Perl 語言中亦具備常見的條件結講與迴圈結構。
if ($var) { if ($var) {
... ...
@ -137,9 +134,9 @@ if ($var) {
unless (condition) { unless (condition) {
... ...
} }
# This is provided as a more readable version of "if (!condition)" # 這算是可讀性較好的 "if (!condition)"
# the Perlish post-condition way # 倒裝句型算是某「很 Perl 的」寫法
print "Yow!" if $zippy; print "Yow!" if $zippy;
print "We have no bananas" unless $bananas; print "We have no bananas" unless $bananas;
@ -149,7 +146,7 @@ while (condition) {
} }
my $max = 5; my $max = 5;
# for loops and iteration # 以 for 迴圈,$i 為迭代變數
for my $i (0 .. $max) { for my $i (0 .. $max) {
print "index is $i"; print "index is $i";
} }
@ -160,68 +157,63 @@ for my $element (@elements) {
map {print} @elements; map {print} @elements;
# implicitly # 迭代變數為 $_
for (@elements) { for (@elements) {
print; print;
} }
# iterating through a hash (for and foreach are equivalent) # 對雜湊進行迭代for 與 foreach 完全相同)
foreach my $key (keys %hash) { foreach my $key (keys %hash) {
print $key, ': ', $hash{$key}, "\n"; print $key, ': ', $hash{$key}, "\n";
} }
# the Perlish post-condition way again # 又是「很 Perl 的」倒裝句法
print for @elements; print for @elements;
# iterating through the keys and values of a referenced hash # 對一雜湊參照之中迭代,逐一走過其鍵與值
print $hash_ref->{$_} for keys %$hash_ref; print $hash_ref->{$_} for keys %$hash_ref;
#### Regular expressions #### 正規表示式
# Perl's regular expression support is both broad and deep, and is the # Perl 中,對正規表示式的支援既廣亦深,在 perlrequick、perlretut 等各處文件中
# subject of lengthy documentation in perlrequick, perlretut, and # 都有更加完整的文件。不過,簡而言之:
# elsewhere. However, in short:
# Simple matching # 簡易比對
if (/foo/) { ... } # true if $_ contains "foo" if (/foo/) { ... } # 若 $_ 內含 "foo" 則為真
if ($x =~ /foo/) { ... } # true if $x contains "foo" if ($x =~ /foo/) { ... } # 若 $x 內含 "foo" 則為真
# Simple substitution # 簡易取代
$x =~ s/foo/bar/; # 將 $x 中第一個出現的 foo 換為 bar
$x =~ s/foo/bar/g; # 將 $x 中所有出現的 foo 換為 bar
$x =~ s/foo/bar/; # replaces foo with bar in $x #### 檔案與輸出入
$x =~ s/foo/bar/g; # replaces ALL INSTANCES of foo with bar in $x
# 以 "open" 函式開檔後,便可自檔案輸入或對其輸出
#### Files and I/O # 讀檔:
# You can open a file for input or output using the "open()" function.
# For reading:
open(my $in, "<", "input.txt") or die "Can't open input.txt: $!"; open(my $in, "<", "input.txt") or die "Can't open input.txt: $!";
# For writing (clears file if it exists):
# 寫檔(若檔案已經存在,舊內容會被清空):
open(my $out, ">", "output.txt") or die "Can't open output.txt: $!"; open(my $out, ">", "output.txt") or die "Can't open output.txt: $!";
# For writing (appends to end of file):
# 寫檔(若檔案已經存在,會寫到檔尾去):
open(my $log, ">>", "my.log") or die "Can't open my.log: $!"; open(my $log, ">>", "my.log") or die "Can't open my.log: $!";
# You can read from an open filehandle using the "<>" operator. In # 使用 "<>" 算符,能對檔案代號進行讀取。在純量語境下,會自檔案代號讀一列內容。
# scalar context it reads a single line from the filehandle, and in list # 而在串列語境下,對讀入整個檔案。每一列都會成為串列中一項元素。
# context it reads the whole file in, assigning each line to an element
# of the list:
my $line = <$in>; my $line = <$in>;
my @lines = <$in>; my @lines = <$in>;
# You can write to an open filehandle using the standard "print" # 以 "print" 函式,則可對檔案代號進行輸出。
# function.
print $out @lines; print $out @lines;
print $log $msg, "\n"; print $log $msg, "\n";
#### Writing subroutines #### 函式之撰寫
# Writing subroutines is easy: # 撰寫函式很是容易:
sub logger { sub logger {
my $logmessage = shift; my $logmessage = shift;
@ -231,16 +223,19 @@ sub logger {
print $logfile $logmessage; print $logfile $logmessage;
} }
# Now we can use the subroutine just as any other built-in function: # 之後,使用起來就與內建函式無異:
logger("We have a logger subroutine!"); logger("We have a logger subroutine!");
#### Modules #### 模組
# A module is a set of Perl code, usually subroutines, which can be used # A module is a set of Perl code, usually subroutines, which can be used
# in other Perl code. It is usually stored in a file with the extension # in other Perl code. It is usually stored in a file with the extension
# .pm so that Perl can find it. # .pm so that Perl can find it.
# 所謂模組,就是一組 Perl 程式碼,由一些函式組成,並可讓其他 Perl 程式碼來利用。
# 為了讓 perl 能找至,通常模組之副標名為 .pm 。
package MyModule; package MyModule;
use strict; use strict;
use warnings; use warnings;
@ -254,24 +249,21 @@ sub trim {
1; 1;
# From elsewhere: # 自他處利用:
use MyModule; use MyModule;
MyModule::trim($string); MyModule::trim($string);
# The Exporter module can help with making subroutines exportable, so # Exporter 模組能將函式出口,好讓它們能被這樣利用:
# they can be used like this:
use MyModule 'trim'; use MyModule 'trim';
trim($string); trim($string);
# Many Perl modules can be downloaded from CPAN (http://www.cpan.org/) # 有許多 Perl 模組能從 CPAN (https://www.cpan.org) 下載下來,各式各樣的機能讓你
# and provide a range of features to help you avoid reinventing the # 能免於重新發明輪子。不少高人氣模組,如 Exporter則是與 Perl 一同釋出、散佈。
# wheel. A number of popular modules like Exporter are included with # 更多關於 Perl 模組的細節,詳見 perlmod 文件。
# the Perl distribution itself. See perlmod for more details on modules
# in Perl.
#### Objects #### 物件
# Objects in Perl are just references that know which class (package) # Objects in Perl are just references that know which class (package)
# they belong to, so that methods (subroutines) called on it can be # they belong to, so that methods (subroutines) called on it can be
@ -279,6 +271,11 @@ trim($string);
# to set this up. However, you never need to call it yourself if you use # to set this up. However, you never need to call it yourself if you use
# a module like Moose or Moo (see below). # a module like Moose or Moo (see below).
# Perl 中的物件只是個參照但同時又知道自己屬於哪個類別package於是對自身
# 調用方法(函式)時方知去何處尋找函式本體。在建構子(通常是 "new")中,都是以
# "bless" 函式來標記參照與其類別。只不過,若你使用像 Moose 或 Moo 模組的話,這些
# 都不必自己來(總之請繼續往下讀)。
package MyCounter; package MyCounter;
use strict; use strict;
use warnings; use warnings;
@ -301,21 +298,18 @@ sub increment {
1; 1;
# Methods can be called on a class or object instance with the arrow # 以箭頭運算符,便可對某類別或某物件呼叫某方法:
# operator.
use MyCounter; use MyCounter;
my $counter = MyCounter->new; my $counter = MyCounter->new;
print $counter->count, "\n"; # 0 print $counter->count, "\n"; # 0
$counter->increment; $counter->increment;
print $counter->count, "\n"; # 1 print $counter->count, "\n"; # 1
# The modules Moose and Moo from CPAN can help you set up your object # CPAN 上的 Moose 與 Moo 模組能助你撰寫類別本體。它們提供了建構子,與簡單易懂的
# classes. They provide a constructor and simple syntax for declaring # 語法能來宣告屬性。前述的類別改寫之後,如下:
# attributes. This class can be used equivalently to the one above.
package MyCounter; package MyCounter;
use Moo; # imports strict and warnings use Moo; # 同時也啟用 strict 與 warnings
has 'count' => (is => 'rwp', default => 0, init_arg => undef); has 'count' => (is => 'rwp', default => 0, init_arg => undef);
@ -326,17 +320,18 @@ sub increment {
1; 1;
# Object-oriented programming is covered more thoroughly in perlootut, # 物件導向程式設計於 perlootut 文件中有詳盡的說明同時perlobj 文件中更函蓋了
# and its low-level implementation in Perl is covered in perlobj. # 底層實做之細節。
``` ```
#### FAQ #### 常見問答集
perlfaq contains questions and answers related to many common tasks, and often provides suggestions for good CPAN modules to use. perlfaq 文件內含了許多問與答都是關於常遇到的問題與工作也對其提供一些建議與好
用的 CPAN 模組
#### Further Reading #### 延伸閱讀
- [perl-tutorial](http://perl-tutorial.org/) - [perl-tutorial](http://perl-tutorial.org/)
- [Learn at www.perl.com](http://www.perl.org/learn.html) - [Learn Perl](https://www.perl.org/learn.html)
- [perldoc](http://perldoc.perl.org/) - [perldoc](http://perldoc.perl.org/)
- and perl built-in : `perldoc perlintro` - 內建函式 : `perldoc perlintro`