Apple Newton Utilities Uživatelská příručka stáhnout pdf (Strana 847)

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CHAPTER 23

Endpoint Interface

Using the Endpoint Interface 23-19

Handling Unexpected Completion 23

The CompletionScript message is sent to the input spec frame when the input

spec completes unexpectedly—for example, because of a time-out expiring or a

Cancel message.

If you do not specify a

CompletionScript method in your input spec frame, an

exception is forwarded to the endpoint

ExceptionHandler method.

Special Considerations 23

If you want to set up an input spec, but you never want to terminate the input, you

can set up the input form to be either

'string or 'bytes data, and not deﬁne

any of the data termination conditions. In this case, it is up to you to read and ﬂush

the input. You can do this by using a

PartialScript method that calls the

FlushPartial method at the appropriate times. Note that if the input exceeds

the

discardAfter size, the oldest data in the buffer is deleted to reduce the size

of the input.

Alternatively, if you omit the

InputScript method, yet deﬁne the input data

form and termination conditions, the input continues to be terminated and ﬂushed

at the appropriate times. The only difference is that without an

InputScript

method, you'll never see the complete input.

Receiving Data Using Alternative Methods 23

The methods described in this section allow you to receive data in ways other than

letting an input spec terminate normally. You may not need to use these methods;

they're provided for ﬂexibility in handling special situations.

You can force the system to send a pending input spec the

InputScript message

by calling the

Input method. Note that this method is appropriate to use only

when receiving data of the forms

'string and 'bytes. Also, in an InputScript

method that is called as a result of calling

Input, you cannot use SetInputSpec

to change or terminate the input spec. Instead, you must ﬁrst send the

Cancel

message to cancel the current input spec.

You can look at incoming data outside the scope of your

InputScript or

PartialScript method by calling the method Partial. This method returns

data from the input buffer but doesn’t remove it from the buffer. You can use this

method to sample incoming data without affecting the normal operation of your

input spec and its callback methods. Note that this method is appropriate to use

only when receiving data of the forms

'string and 'bytes.

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