* sale, use or other dealings in this Software without prior written *
* authorization. *
****************************************************************************
- * @Id: form_fieldtype.3x,v 1.23 2020/10/24 09:05:17 tom Exp @
+ * @Id: form_fieldtype.3x,v 1.28 2020/12/12 17:11:21 tom Exp @
-->
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</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
+
+</PRE><H3><a name="h3-new_fieldtype">new_fieldtype</a></H3><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 predi-
- cate can see the field's buffer, sizes and other attributes; the second
- argument is an argument-block structure, about which more below.
+ validation. Its parameters are function pointers:
+
+ <EM>field</EM><STRONG>_</STRONG><EM>check</EM>
+ This function checks the validity of an entered data string when-
+ ever the user attempts to leave a field. It has two arguments:
+
+ <STRONG>o</STRONG> The (FIELD *) argument is passed in so the validation predi-
+ cate can see the field's buffer, sizes and other attributes.
+
+ <STRONG>o</STRONG> The second argument is an argument-block structure, about
+ which more below.
+
+ <EM>char</EM><STRONG>_</STRONG><EM>check</EM>
+ 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.
- 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 vali-
- dation type.
+</PRE><H3><a name="h3-free_fieldtype">free_fieldtype</a></H3><PRE>
+ The <STRONG>free_fieldtype</STRONG> function frees the space allocated for a given vali-
+ dation type by <STRONG>new_fieldtype</STRONG>.
+
+</PRE><H3><a name="h3-set_fieldtype_arg">set_fieldtype_arg</a></H3><PRE>
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
- argument-block object which can later be passed to validation predi-
- cated. 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.
+ functions with a field type:
+
+ <EM>make</EM><STRONG>_</STRONG><EM>arg</EM>
+ This function is automatically applied to the list of arguments
+ you give <STRONG>set_field_type</STRONG> when attaching validation to a field. It
+ stores the arguments in an allocated argument-block object which
+ is used when validating input.
+
+ <EM>copy</EM><STRONG>_</STRONG><EM>arg</EM>
+ This function may be used by applications to copy argument-blocks.
+
+ <EM>free</EM><STRONG>_</STRONG><EM>arg</EM>
+ Frees an argument-block structure.
+ 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, the form library assumes that
+ <EM>make</EM><STRONG>_</STRONG><EM>arg</EM> 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 <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> function allows forms programmers to define
+ successor and predecessor functions for the field type. These func-
+ tions take the field pointer and an argument-block structure as argu-
+ ments.
+
+
+</PRE><H3><a name="h3-link_fieldtype">link_fieldtype</a></H3><PRE>
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_field-</STRONG>
- <STRONG>type_choice</STRONG> 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 arguments.
-
</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
The pointer-valued routines return NULL on error. They set <STRONG>errno</STRONG>
</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
- <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="form.3x.html">form(3x)</A></STRONG>.
+ <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="form.3x.html">form(3x)</A></STRONG>, <STRONG><A HREF="form_field_validation.3x.html">form_field_validation(3x)</A></STRONG>.
</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
The header file <STRONG><form.h></STRONG> automatically includes the header file
<STRONG><curses.h></STRONG>.
- All of the <STRONG>(char</STRONG> <STRONG>*)</STRONG> arguments of these functions should actually be
- <STRONG>(void</STRONG> <STRONG>*)</STRONG>. The type has been left uncorrected for strict compatibility
- with System V.
-
</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
These routines emulate the System V forms library. They were not sup-
<ul>
<li><a href="#h2-NAME">NAME</a></li>
<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
-<li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
+<li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
+<ul>
+<li><a href="#h3-new_fieldtype">new_fieldtype</a></li>
+<li><a href="#h3-free_fieldtype">free_fieldtype</a></li>
+<li><a href="#h3-set_fieldtype_arg">set_fieldtype_arg</a></li>
+<li><a href="#h3-set_fieldtype_choice">set_fieldtype_choice</a></li>
+<li><a href="#h3-link_fieldtype">link_fieldtype</a></li>
+</ul>
+</li>
<li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
<li><a href="#h2-NOTES">NOTES</a></li>
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