How past this usefull information on harbour doc?
Where?
without this operation
a lot of user can't use assicuative hash array
2010/5/25 Przemysław Czerpak <dru...@acn.waw.pl>
> On Tue, 25 May 2010, Szak�ts Viktor wrote:
>
> Hi,
>
> > That sounds great, may I ask for a simple example which
> > show the usefulness of this feature over regular hashes?
>
>
> This code illustrates the difference between regular and
> associative hash arrays:
>
> proc main()
> local h
> h := { => }
> ? "regular hash array"
> tst( h )
> h := { => }
> ? "associative hash array"
> hb_hKeepOrder( h, .T. )
> tst( h )
> return
> proc tst( h )
> local v, i
> h[ 'zxc' ] := 1.000
> h[ 'qwe' ] := 2.000
> h[ 'abc' ] := 3.000
> h[ 'dfg' ] := 4.000
> h[ 'rbc' ] := 5.000
> ? "for each:"
> for each v in h
> ? v:__enumIndex(), v:__enumKey(), v
> next
> ? "access by index:"
> for i := 1 to len( h )
> ? i, hb_hValueAt( h, i )
> next
> ?
> return
>
> As you can see executing it the order of items in associative array
> is strictly defined and it's the same as the order in which new item
> were added. It means that you have two strictly defined indexes. One
> which can be used with [] operator and any hash item keys and the
> second numeric only index. It's usable in many different places.
> This is the part of ChangeLog message I created for Harbour OLE
> servers. It's very nice example of practical usage.
>
> <hAction> is optional parameter with hash array containing messages
> and instance variables used by OLE server. The keys in hash array
> are strings with message names and values are actions. Codeblock
> and symbol items means that given message is a method call and
> any other value means that it's variable.
> By default the same hash array is shared between all objects
> created by registered server. It's important when hash array
> contains values which are neither codeblock nor symbol items
> so they are not used as method but rather as instance variables
> because such instance variables are shared between OLE objects.
> Setting 4-th parameter <lHashClone> to .T. causes that each
> objects receives it's own copy of <hAction> item so instance
> variables inside hash array are also local to OLE object.
> Alternatively programmer can use <bAction> or <sAction> to create
> seprate copy of hash array for each object, i.e.:
> bAction := {|| hb_hClone( hValue ) }
> When hash array contains symbol item (@funcName()) then when it's
> executed by OLE object message it's possible to access the hash
> array bound with given OLE object using QSelf() function. It maybe
> useful if hash array contains instance variables and programmer
> wants to access them.
> Please remember that using hash array which was initialized to keep
> original assign order by HB_HKEEPORDER( <hAction>, .T. ) before
> adding its items you can define strict message numbers (DISPIDs), i.e.:
> hAction := {=>}
> HB_HKEEPORDER( hAction, .T. )
> hAction[ "OPEN" ] := @myole_open() // DISPID=1
> hAction[ "CLOSE" ] := @myole_close() // DISPID=2
> hAction[ "SAVE" ] := @myole_save() // DISPID=3
> hAction[ "LOAD" ] := @myole_load() // DISPID=4
> hAction[ "PRINT" ] := @myole_print() // DISPID=5
> (see example in olesrv2.prg)
>
> best regards,
> Przemek
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>
--
Massimo Belgrano
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