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# Pointer

class `Pointer`
  Syntax:

    `Pointer(&x)`

    `Pointer("variable")`

    `Pointer(&x, "stmt that may contain $1")`

    `Pointer("variable", "stmt that may contain $1 or variable name")`

  Description:

    Holds a reference to a variable. When memory for the variable is freed, the Pointer will return an error if used.

    See `Pointer.assign()` for the meaning of the optional second arg.

`Pointer.``val`()
  Syntax:

    `x = ptr.val`

    `ptr.val = expr`

  Description:
    Returns the value of the variable pointed to by ptr or, if the left hand side of an assignment, sets the value of the variable.

`Pointer.``s`()
  Syntax:
    `str = ptr.s`
  Description:
    If the Pointer was constructed with the name of a variable, that name can be retrieved as a strdef.

`Pointer.``assign`()
  Syntax:
    `x = ptr.assign(val)`
  Description:

    Sets the value of the pointer variable to val. If prt was constructed with a second arg then the execution depends on its form. If the second arg string contains one or more $1 tokens, then the tokens are replaced by `hoc_ac_`, `hoc_ac_` is set to the val and the resulting statement is executed. Otherwise the second arg string is assumed to be a variable name and a statement of the form variablename = `hoc_ac_` is executed. Note that the compiling of these statements takes place just once when the Pointer is constructed. Thus ptr.assign(val) is marginally faster than execute(“stmt with val”).

    (following not implemented) And if the stmt is a variablename then the pointer is used and all interpreter overhead is avoided. Also note that on construction, the second arg variable is executed with the value of the first arg pointer. So

    Returns val.

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