-</PRE>
-<H2>DESCRIPTION</H2><PRE>
- The function <STRONG>new_fieldtype</STRONG> creates a new field type usable
- for data validation. You supply it with <EM>field</EM><STRONG>_</STRONG><EM>check</EM>, a
- predicate to check the validity of an entered data string
- whenever the user attempts to leave a field. The (FIELD
- *) argument is passed in so the validation predicate can
- see the field's buffer, sizes and other attributes; the
- second argument is an argument-block structure, about
- which more below.
-
- You also supply <STRONG>new_fieldtype</STRONG> with <EM>char</EM><STRONG>_</STRONG><EM>check</EM>, a function
- to validate input characters as they are entered; it will
- be passed the character to be checked and a pointer to an
- argument-block structure.
-
- The function <STRONG>free_fieldtype</STRONG> frees the space allocated for
- a given validation type.
-
- The function <STRONG>set_fieldtype_arg</STRONG> associates three storage-
- management functions with a field type. The <EM>make</EM><STRONG>_</STRONG><EM>arg</EM>
- function is automatically applied to the list of arguments
- you give <STRONG>set_field_type</STRONG> when attaching validation to a
- field; its job is to bundle these into an allocated argu-
- ment-block object which can later be passed to validation
- predicated. The other two hook arguments should copy and
- free argument-block structures. They will be used by the
- forms-driver code. You must supply the <EM>make</EM><STRONG>_</STRONG><EM>arg</EM> function,
- the other two are optional, you may supply NULL for them.
- In this case it is assumed that <EM>make</EM><STRONG>_</STRONG><EM>arg</EM> does not allocate
- memory but simply loads the argument into a single scalar
- value.
-
- The function <STRONG>link_fieldtype</STRONG> creates a new field type from
- the two given types. They are connected by an logical
- 'OR'.
-
- The form driver requests <STRONG>REQ_NEXT_CHOICE</STRONG> and
- <STRONG>REQ_PREV_CHOICE</STRONG> assume that the possible values of a field
- form an ordered set, and provide the forms user with a way
- to move through the set. The <STRONG>set_fieldtype_choice</STRONG> func-
- tion allows forms programmers to define successor and
- predecessor functions for the field type. These functions
- take the field pointer and an argument-block structure as
+ <B>int</B> <B>set_fieldtype_arg(</B>
+ <B>FIELDTYPE</B> <B>*</B><I>fieldtype</I><B>,</B>
+ <B>void</B> <B>*(*</B> <B>const</B> <I>make</I><B>_</B><I>arg</I><B>)(va_list</B> <B>*),</B>
+ <B>void</B> <B>*(*</B> <B>const</B> <I>copy</I><B>_</B><I>arg</I><B>)(const</B> <B>void</B> <B>*),</B>
+ <B>void</B> <B>(*</B> <B>const</B> <I>free</I><B>_</B><I>arg</I><B>)(void</B> <B>*));</B>
+ <B>int</B> <B>set_fieldtype_choice(</B>
+ <B>FIELDTYPE</B> <B>*</B><I>fieldtype</I><B>,</B>
+ <B>bool</B> <B>(*</B> <B>const</B> <I>next</I><B>_</B><I>choice</I><B>)(FIELD</B> <B>*,</B> <B>const</B> <B>void</B> <B>*),</B>
+ <B>bool</B> <B>(*</B> <B>const</B> <I>prev</I><B>_</B><I>choice</I><B>)(FIELD</B> <B>*,</B> <B>const</B> <B>void</B> <B>*));</B>
+
+ <B>FIELDTYPE</B> <B>*link_fieldtype(FIELDTYPE</B> <B>*</B><I>type1</I><B>,</B>
+ <B>FIELDTYPE</B> <B>*</B><I>type2</I><B>);</B>
+
+
+</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
+
+</PRE><H3><a name="h3-new_fieldtype">new_fieldtype</a></H3><PRE>
+ The function <B>new_fieldtype</B> creates a new field type usable for data
+ validation. Its parameters are function pointers:
+
+ <I>field</I><B>_</B><I>check</I>
+ This function checks the validity of an entered data string
+ whenever the user attempts to leave a field. It has two
+ arguments:
+
+ <B>o</B> The (FIELD *) argument is passed in so the validation
+ predicate can see the field's buffer, sizes and other
+ attributes.
+
+ <B>o</B> The second argument is an argument-block structure, about
+ which more below.
+
+ <I>char</I><B>_</B><I>check</I>
+ This function validates input characters as they are entered. The
+ form library passes it the character to be checked and a pointer
+ to an argument-block structure.
+
+
+</PRE><H3><a name="h3-free_fieldtype">free_fieldtype</a></H3><PRE>
+ The <B>free_fieldtype</B> function frees the space allocated for a given
+ validation type by <B>new_fieldtype</B>.
+
+
+</PRE><H3><a name="h3-set_fieldtype_arg">set_fieldtype_arg</a></H3><PRE>
+ The function <B>set_fieldtype_arg</B> associates three storage-management
+ functions with a field type:
+
+ <I>make</I><B>_</B><I>arg</I>
+ This function is automatically applied to the list of arguments
+ you give <B>set_field_type</B> when attaching validation to a field. It
+ stores the arguments in an allocated argument-block object which
+ is used when validating input.
+
+ <I>copy</I><B>_</B><I>arg</I>
+ This function may be used by applications to copy argument-blocks.
+
+ <I>free</I><B>_</B><I>arg</I>
+ Frees an argument-block structure.
+
+ You must supply the <I>make</I><B>_</B><I>arg</I> function. The other two are optional: you
+ may supply NULL for them. In this case, the form library assumes that
+ <I>make</I><B>_</B><I>arg</I> does not allocate memory but simply loads the argument into a
+ single scalar value.
+
+
+</PRE><H3><a name="h3-set_fieldtype_choice">set_fieldtype_choice</a></H3><PRE>
+ The form driver requests <B>REQ_NEXT_CHOICE</B> and <B>REQ_PREV_CHOICE</B> assume
+ that the possible values of a field form an ordered set, and provide
+ the forms user with a way to move through the set.
+
+ The <B>set_fieldtype_choice</B> function allows forms programmers to define
+ successor and predecessor functions for the field type. These
+ functions take the field pointer and an argument-block structure as