fieldtype(3FORM)

💖 fieldtype — it's giving "define validation-field types" ✨

okay bestie, so this page is fieldtype(3FORM) from the library calls girlies, and it's literally all about teaching forms how to check their own homework. form_fieldtype is the NAME, and the vibe is custom validation types, periodt. 🎀

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🌸 SYNOPSIS 🌸

#include <form.h>

FIELDTYPE *new_fieldtype(
    bool (* const field_check)(FIELD *, const void *),
    bool (* const char_check)(int, const void *));
int free_fieldtype(FIELDTYPE *fieldtype);

int set_fieldtype_arg(
    FIELDTYPE *fieldtype,
    void *(* const make_arg)(va_list *),
    void *(* const copy_arg)(const void *),
    void  (* const free_arg)(void *));
int set_fieldtype_choice(
    FIELDTYPE *fieldtype,
    bool (* const next_choice)(FIELD *, const void *),
    bool (* const prev_choice)(FIELD *, const void *));

FIELDTYPE *link_fieldtype(FIELDTYPE *type1,
                          FIELDTYPE *type2);

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🦋 DESCRIPTION 🦋

✨ new_fieldtype ✨

The function new_fieldtype creates a new field type usable for data validation. Its parameters are function pointers:

• field_check — this function checks the validity of an entered data string whenever the user attempts to leave a field. It has two arguments:
  • 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. (yes bestie, it's coming, hold on 😭)
• char_check — 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. one character at a time, like a bouncer at the club door 💅

✨ free_fieldtype ✨

The free_fieldtype function frees the space allocated for a given validation type by new_fieldtype. give it back to the universe, queen 🌈

✨ set_fieldtype_arg ✨

The function set_fieldtype_arg associates three storage-management functions with a field type:

• make_arg — this function is automatically applied to the list of arguments you give set_field_type when attaching validation to a field. It stores the arguments in an allocated argument-block object which is used when validating input.
• copy_arg — this function may be used by applications to copy argument-blocks.
• free_arg — frees an argument-block structure.

You must supply the make_arg function. The other two are optional: you may supply NULL for them. In this case, the form library assumes that make_arg does not allocate memory but simply loads the argument into a single scalar value. ngl that's the lazy-girl path and honestly? valid 🫶

✨ set_fieldtype_choice ✨

The form driver requests REQ_NEXT_CHOICE and REQ_PREV_CHOICE 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 set_fieldtype_choice 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. so like, next and previous buttons but make it yours ✨

✨ link_fieldtype ✨

The function link_fieldtype creates a new field type from the two given types. They are connected by a logical “or”. it's giving collab 🎀 two types, one iconic union, iykyk

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💀 RETURN VALUE 💀

The pointer-valued routines return NULL on error. They set errno according to their success:

• E_OK — the routine succeeded. 🎉
• E_BAD_ARGUMENT — routine detected an incorrect or out-of-range argument. bestie what did you do 😭
• E_SYSTEM_ERROR — system error occurred, e.g., malloc failure. 💀

The integer-valued routines return one of the following codes on error:

• E_OK — the routine succeeded. 👑
• E_BAD_ARGUMENT — routine detected an incorrect or out-of-range argument.
• E_CONNECTED — the field is already connected to a form.
• E_CURRENT — the field is the current field.
• E_SYSTEM_ERROR — system error occurred (see errno(3)).

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🌈 PORTABILITY 🌈

These routines emulate the System V forms library. They were not supported on Version 7 or BSD versions. so like, vintage-only energy, no cap 🧚

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👑 AUTHORS 👑

Juergen Pfeifer. Manual pages and adaptation for new curses by Eric S. Raymond. absolute legends, we stan 🌟

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🌸 SEE ALSO 🌸

• ncurses(3NCURSES)
• form(3FORM)
• field_validation(3FORM)

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and that's the whole page bestie, every flag and every detail intact, fr fr 💖

mwah 💋 this was ncurses 6.6, dated 2025-01-18 — fieldtype(3FORM), signing off, slay 🎀✨