Miranda conformTo

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'''__conformTo/1''' is a [[Miranda message]].
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<code>__conformTo/1</code> is a Miranda message.
{{instance msgdoc|__conformTo|1|<var>guard</var> :[[Guard]]|[[any]]}}
{{instance msgdoc|__conformTo|1|<var>guard</var> :[[Guard]]|[[any]]}}
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  # value: <obj>
  # value: <obj>
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==Original Javadoc==
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{{stub}}
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{{XXX|merge}}
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When a guard doesn't succeed by itself at coercing an object, the guard
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may enlists the object's aid in bring about a coercion it would find
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acceptable.
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A guard enlists the object's aid at the price of being
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[http://www.sims.berkeley.edu/~ping/auditors/ Gozarian]. A
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Gozarian guard wants to enlists the object's aid <i>because</i> it is
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ignorant of the kind of object it's dealing with, so a generic protocol
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is needed. That's why __conformTo/1 is provided as a MirandaMethod.
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The guard asks the object to conform to some guard that the object may
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know about. Often this will be the guard that's attempting the coercion.
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An object should attempt to return a representation of itself that the
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argument guard would succeed in coercing. A requesting guard should then
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try again on the result, but if this doesn't coerce, it should fail
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there rather than making further __conformTo/1 requests. This implies
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that it's the responsibility of the object's __conformTo/1
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implementation to do any iteration needed for multi-step conversions.
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The default (Miranda) implementation of __conformTo/1 just returns
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self.
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[[Category:Miranda messages]]
[[Category:Miranda messages]]
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[[Category:ELib specification]]

Revision as of 16:55, 21 August 2009

__conformTo/1 is a Miranda message.

Contents

__conformTo/1

Signature: __conformTo(guard :Guard) :any

Clients

A guard which does not immediately accept the recipient may call __conformTo(the guard) on it, and check and return the result thereof instead.

Implementations

Implementations of __conformTo/1 should return the recipient if they have no better answer.

Miranda behavior

Returns the recipient. 

? def obj {}
> obj.__conformTo(any)
# value: <obj>

? obj.__conformTo(List)
# value: <obj>

? obj.__conformTo(def bobj {})
# value: <obj>

? obj.__conformTo(null)
# value: <obj>
This page is a stub; it should be expanded with more information. If doing so, check the original E web site and the mailing list archives for content which could be moved into this page.
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