JVCL Help:DP SelectConsumerContext
JVCL Help: DP_SelectConsumerContext procedure
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Selects a new consumer and context.
Pascal
run\JvDataProvider.pas
procedureDP_SelectConsumerContext(Provider: IJvDataProvider; Consumer: IJvDataConsumer; Context: IJvDataContext);
Parameters
| Parameters | Description |
| Provider: IJvDataProvider | Reference to the IJvDataProvider to select a new consumer and context for. |
| Consumer: IJvDataConsumer | Reference to the consumer to select as the active consumer. |
| Context: IJvDataContext | Reference to the context to select as the active context. |
Description
DP_SelectConsumerContext selects a new consumer and context pair as the active consumer and context of a provider. The current consumer and context are pushed onto a stack. Use DP_ReleaseConsumerContext to return to them. When the provider is created no consumer is selected.
This routine in combination with DP_ReleaseConsumerContext allows the selection/deselection of a consumer and it's active context to be performed atomically. If one of the selection action fails, the other will be reverted automatically.
Most consumers will use this routine to select itself and it's associated context into the provider before making other requests from the provider.
It's highly recommended to keep the timespan of the selection as short as possible, i.e. select the consumer/context, access the provider, release the consumer/context and always guard the code between selection and release with a try/finally to make sure the release of the consumer/context takes place:DP_SelectConsumerContext(Provider, Consumer, Context);
try
... access the provider here ...
finally
DP_ReleaseConsumerContext(Provider);
end;
See Also
DP_ReleaseConsumerContext, IJvDataProvider.SelectConsumer, IJvDataProvider.SelectContext
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