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C H A P T E R 2 3
Endpoint Interface
About the Endpoint Interface
23-5
The different types of data forms and the defaults are described in more detail in
"Data Form Symbols" (Table 20-1 on page 20-2) in Newton Programmer's
Reference
.
Only a subset of data form values is applicable for any particular operation.
Table 23-1 enumerates the data forms and their applicability to output specs, input
specs, and endpoint option frames.
Template Data Form
23
The
'template
data form enables you to pass data as if you were passing C
structures, and is thus extremely useful in communicating with the lower level
communication tools in getting and setting endpoint options.
When you set options or send data using the
'template
data form, the data is
expected to be a frame containing two slots,
arglist
and
typelist
. The
arglist
slot is an array containing the data, the list of arguments. The
typelist
slot is a corresponding array containing the types that describe the data.
To get endpoint options, the data in the
data
slot must be a frame containing the
arglist
and
typelist
arrays. The
arglist
array should contain placeholder
or default values. The system supplies the actual
arglist
values when the option
list is returned.
In the same manner, to receive data, you must add a
target
slot to your input
spec containing the
arglist
and
typelist
arrays. The
arglist
array contains
Table 23-1
Data form applicability
Data form
Output spec
Input spec
Option frame
'char
default for characters
OK
OK
'number
default for numbers
OK
OK
'string
default for strings
default
OK
'bytes
OK OK
OK
'binary
default for binary objects;
output spec can include
optional
target
slot
OK; input spec
must include
target
slot
OK
'template
OK
OK; input spec
must include
target
slot
default
'frame
OK
OK
not applicable
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