# Reflection¶

Usage

use Reflection;


Functions for finding out about fields, functions, and methods.

Note

There are several ways in which this module could be improved upon:

• the methods here might be better as type methods, so you could use R.numFields() instead of numFields(R).
• getField does not yet return a mutable value.
proc numFields(type t) param: int

Return the number of fields in a class or record as a param. The count of fields includes types and param fields.

proc getFieldName(type t, param i: int) param: string

Get the name of the ith field in a class or record. Causes a compilation error if i is not in 1..numFields(t).

Arguments: t -- a class or record type i -- which field to get the name of the name of the field, as a param string
proc getField(const ref x: ?t, param i: int) param

Get the ith field in a class or record. When the ith field is a param this overload will be chosen to return a param. Causes a compilation error if i is not in 1..numFields(t).

Arguments: x -- a class or record i -- which field to get the param that field represents
proc getField(const ref x: ?t, param i: int) type

Get the ith field in a class or record. When the ith field is a type variable this overload will be chosen to return a type. Causes a compilation error if i is not in 1..numFields(t).

Arguments: x -- a class or record i -- which field to get the type that field represents
proc getField(const ref x: ?t, param i: int) const ref

Get the ith field in a class or record. Causes a compilation error if i is not in 1..numFields(t).

Arguments: x -- a class or record i -- which field to get an rvalue referring to that field.
proc getField(const ref x: ?t, param s: string) param

Get a field in a class or record by name. When the named field is a param this overload will be chosen to return a param. Will generate a compilation error if a field with that name is not found.

Arguments: x -- a class or record s -- the name of a field the param that field represents
proc getField(const ref x: ?t, param s: string) type

Get a field in a class or record by name. When the named field is a type variable this overload will be chosen to return a type. Will generate a compilation error if a field with that name is not found.

Arguments: x -- a class or record s -- the name of a field the type that field represents
proc getField(const ref x: ?t, param s: string) const ref

Get a field in a class or record by name. Will generate a compilation error if a field with that name is not found.

Arguments: x -- a class or record s -- the name of a field an rvalue referring to that field.
proc getFieldRef(ref x: ?t, param i: int) ref

Get a mutable ref to the ith field in a class or record. Causes a compilation error if i is not in 1..numFields(t) or if the argument is not mutable.

Arguments: x -- a class or record i -- which field to get an rvalue referring to that field.
proc getFieldRef(ref x: ?t, param s: string) ref

Get a mutable ref to a field in a class or record by name. Will generate a compilation error if a field with that name is not found or if the class or record is not mutable.

Arguments: x -- a class or record s -- the name of a field an rvalue referring to that field.
proc getFieldIndex(type t, param s: string) param: int

Get a field index in a class or record, or 0 if the field is not found.

Arguments: t -- a class or record type s -- the name of a field an index i usable in getField, or 0 if the field was not found.
proc hasField(type t, param s: string) param: bool

Returns true if a class or record has a field named s, or false otherwise.

Arguments: t -- a class or record type s -- the name of a field true if the field is present.
proc canResolve(param fname: string) param: bool

Returns true if a function named fname taking no arguments could be called in the current scope.

proc canResolve(param fname: string, args ...) param: bool

Returns true if a function named fname taking the arguments in args could be called in the current scope.

proc canResolveMethod(obj, param fname: string) param: bool

Returns true if a method named fname taking no arguments could be called on obj in the current scope.

proc canResolveMethod(obj, param fname: string, args ...) param: bool

Returns true if a method named fname taking the arguments in args could be called on obj in the current scope.

proc canResolveTypeMethod(type t, param fname: string) param: bool

Returns true if a type method named fname taking no arguments could be called on type t in the current scope.

proc canResolveTypeMethod(type t, param fname: string, args ...) param: bool

Returns true if a type method named fname taking the arguments in args could be called on type t in the current scope.