Next: Records, Previous: Symbols, Up: Miscellaneous Datatypes [Contents][Index]
Parameters are objects that can be bound to new values for the duration of a dynamic extent. See Dynamic Binding.
Returns a newly allocated parameter object, which is a procedure that
accepts zero arguments and returns the value associated with the
parameter object. Initially this value is the value of
(converter init), or of init if the conversion procedure
converter is not specified. The associated value can be
temporarily changed using the parameterize special form
(see parameterize).
The make-parameter procedure is standardized by SRFI 39 and
by R7RS, while make-unsettable-parameter is an MIT/GNU
Scheme extension.
This procedure is like make-parameter, except that the returned
parameter object may also be assigned by passing it an argument. Note
that an assignment to a settable parameter affects only the extent of
its current binding.
make-settable-parameter is an MIT/GNU Scheme extension.
Bindings should be an alist associating parameter objects with new values. Returns the value of thunk while the parameters are dynamically bound to the values.
Note that the parameterize special form expands into a call to
this procedure. parameterize* is an MIT/GNU Scheme extension.
A cell object is very similar to a parameter but is not implemented in multi-processing worlds and thus is deprecated. Parameters should be used instead.
Returns #t if object is a cell; otherwise returns
#f.
Returns a newly allocated cell whose contents is object.
Returns the current contents of cell.
Alters the contents of cell to be object. Returns an unspecified value.
Alters the contents of cell to be object, calls thunk with no arguments, then restores the original contents of cell and returns the value returned by thunk. This is completely equivalent to dynamic binding of a variable, including the behavior when continuations are used (see Dynamic Binding).
Next: Records, Previous: Symbols, Up: Miscellaneous Datatypes [Contents][Index]