Modern Chan Channel Send

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Send

Sends a value, waiting for room or a receiver; raises an error if the channel is closed.

Syntax

Send( byref v as T ) as boolean

Notes

• RAISES on a closed channel -- it does not return FALSE. Sending after a close is a structural bug: two parties disagree about who owns the producer role, and reporting it as an ordinary FALSE would let that disagreement continue silently.
• On a buffered channel it blocks only while the buffer is full; on a rendezvous channel (capacity 0) it blocks until a receiver arrives.
• On a nil channel it blocks forever. That is deliberate, and is what makes assigning a nil channel disable a select case.
• TrySend is the non-blocking form and SendFor the bounded one.

Examples

#import "std/tasks"
using tasks

dim ch as Channel( of int32 ) = Channel( of int32 )( 2 )

dim as int32 a = 1, b = 2
print ch.Send( a )           '' true
print ch.Send( b )           '' true -- still room in the buffer
print ch.Count( )            '' 2

'' Sending on a CLOSED channel RAISES -- illegal function call, not a
'' FALSE -- so a producer that cannot know must ask first:
dim as int32 got
ch.TryReceive( got )
ch.Close( )
if ch.IsClosed( ) = false then
    dim as int32 c = 3
    ch.Send( c )
end if
print "not sent"

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Library: Goroutines and Channels
Category: Goroutines and Channels
Documented under: Members