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Proxee zef:raku-community-modules last updated on 2022-05-20

README.md
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NAME
====

Proxee — A more usable Proxy with bells

SYNOPSIS
========

```raku
use Proxee;
```

General use:

```raku
# No self as first arg; simply use a regular block in both code blocks:
my @stuff;
my $stuff := Proxee.new: :STORE{ @stuff.push: $_ }, :FETCH{ @stuff.join: ' | ' }
$stuff = 42;
$stuff = 'meow';
say $stuff; # OUTPUT: «42 | meow␤»

# Single block as arg; keep all related bits in one place
my $stuff2 := Proxee.new: {
    my @stuff;
    :STORE{ @stuff.push: $_    },
    :FETCH{ @stuff.join: ' | ' }
}
$stuff2 = 42;
$stuff2 = 'meow';
say $stuff2; # OUTPUT: «42 | meow␤»
```

Special shared dynamic variable:

```raku
# Or just use the special shared variable:
my $stuff2 := Proxee.new: :STORE{ $*PROXEE.push: $_ }, :FETCH{ $*PROXEE.join: ' | ' }
$stuff2 = 42;
$stuff2 = 'meow';
say $stuff2; # OUTPUT: «42 | meow␤»

# Default STORErer
my $cuber := Proxee.new: :FETCH{ $*PROXEE³ };
$cuber = 11;
say $cuber; # OUTPUT: «1331␤»

# Default FETCHer
my $squarer := Proxee.new: :STORE{ $*PROXEE = $_² };
$squarer = 11;
say $squarer; # OUTPUT: «121␤»

# Shortcut to assign to $*PROXEE
my $squarer := Proxee.new: :PROXEE{ $_² };
$squarer = 11;
say $squarer; # OUTPUT: «121␤»
```

Coercers (for backward compatibility only):

```raku
# Coercer types on variables:
my $integral := Proxee.new: Int();
$integral = ' 42.1e0 ';
say $integral; # OUTPUT: «42␤»

# Coercer types on attributes:
class Foo {
    has $.foo is rw;
    submethod TWEAK (:$foo) { ($!foo := Proxee.new: Int()) = $foo }
}
my $o = Foo.new: :foo('42.1e0');
say $o.foo;       # OUTPUT: «42␤»
$o.foo = 12.42;
say $o.foo;       # OUTPUT: «12␤»
```

**Note**: this option is only provided for backwards compatibility. Recent version of Rakudo support coercion types out of the box in variable, parameter and attribute declarations.

DESCRIPTION
===========

The core [`Proxy`](https://docs.raku.org/type/Proxy) type is a bit clunky to use. This module provides an alternative class `Proxee` with an improved interface, and with a few extra features.

METHODS
=======

new
---

```raku
multi method new(\coercer where {.HOW ~~ Metamodel::CoercionHOW})
multi method new(:&PROXEE, :&STORE, :&FETCH)
multi method new(&block)
```

Creates and returns a new [`Proxy`](https://docs.perl6.org/type/Proxy) object whose `:STORE` and `:FETCH` `Callable`s have been set to behave like functionality offered by `Proxee`. Possible arguments are:

### An Improved Proxy

The regular functionality of a [`Proxy`](https://docs.perl6.org/type/Proxy) remains, except the `Proxy` object is no longer passed to neither `:FETCH` nor `:STORE` callables. `:FETCH` gets no args; `:STORE` gets 1 arg, the value being stored:

```raku
my @stuff;
my $stuff := Proxee.new: :STORE{ @stuff.push: $_ }, :FETCH{ @stuff.join: ' | ' }
$stuff = 42;
$stuff = 'meow';
say $stuff; # OUTPUT: «42 | meow␤»
```

In addition, automated storage is available. **Assign** (do not bind, or you'll break it) to `$*PROXEE` variable to store the value in the automated storage and read from it to retrieve that value:

```raku
my $stuff2 := Proxee.new:
  :STORE{ $*PROXEE.push: $_ },
  :FETCH{ $*PROXEE.join: ' | ' }
$stuff2 = 42;
$stuff2 = 'meow';
say $stuff2; # OUTPUT: «42 | meow␤»
```

The `:STORE` argument is optional and **defaults to** `{ $*PROXEE = $_ }`. The `:FETCH` argument is optional and **defaults to** `{ $*PROXEE }`. The `:PROXEE` argument is like `:STORE`, except it also assigns itsi return value to `$*PROXEE`:

```raku
my $squarer := Proxee.new: :PROXEE{ $_² };
$squarer = 11;
say $squarer; # OUTPUT: «121␤»
```

Attempting to use both `:PROXEE` and `:STORE` arguments at the same time will throw `Proxee::X::CannotProxeeStore` exception.

### A Callable

You can also pass a single codeblock as an argument. It will be evaluated and its return value will be used as arguments to `Proxee.new` (after slight massaging to make `Pair`s in a `List` be passed as named args).

This feature exists to make it slightly simpler to use closures with a Proxy:

```raku
my $stuff2 := Proxee.new: {
    my @stuff;
    :STORE{ @stuff.push: $_    },
    :FETCH{ @stuff.join: ' | ' }
}
$stuff2 = 42;
$stuff2 = 'meow';
say $stuff2; # OUTPUT: «42 | meow␤»
```

The above is equivalent to:

```raku
my $stuff2 := do {
    my @stuff;
    Proxee.new: :STORE{ @stuff.push: $_    },
                :FETCH{ @stuff.join: ' | ' }
}
$stuff2 = 42;
$stuff2 = 'meow';
say $stuff2; # OUTPUT: «42 | meow␤»
```

Watch out you don't accidentally pass a block that would be interpreted as a `Hash`:

```raku
Proxy.new:    { :STORE{;}, :FETCH{;} } # WRONG; It's a Hash
Proxy.new: -> { :STORE{;}, :FETCH{;} } # RIGHT; It's a Block
```

### Coercer

Pass a coercer as a positional argument to create a coercing proxy that coerces stored values to specified type:

```raku
my  $Cool-to-Int := Proxee.new: Int(Cool);
$Cool-to-Int = ' 42.70 ';
say $Cool-to-Int; # OUTPUT: «42␤»

$Cool-to-Int = Date.today
# OUTPUT: «Type check failed in Proxee; expected Cool but got Date (Date)␤»
```

**Note**: none of `:&PROXEE`, `:&STORE`, `:&FETCH` can be used together with the coercer argument.

**Note**: this option is only provided for backwards compatibility. Recent version of Rakudo support coercion types out of the box in variable, parameter and attribute declarations.

```raku
my Int(Cool) $Cool-to-Int = ' 42.70';
say $Cool-to-Int; # OUTPUT: «42␤»

$Cool-to-Int = Date.today
# OUTPUT: «Type check failed in Proxee; expected Cool but got Date (Date)␤»
```

AUTHOR
======

Zoffix Znet

COPYRIGHT AND LICENSE
=====================

Copyright 2017 - 2018 Zoffix Znet

Copyright 2019 - 2022 Raku Community

This library is free software; you can redistribute it and/or modify it under the Artistic License 2.0.