RMethodUtils {methods} | R Documentation

## RMethodUtils

### Description

Utility functions to support the definition and use of formal methods. Most of these functions will not normally be called directly by the user.

### Usage

    makeGeneric(f, fdef, keepMethods=TRUE, useAsDefault=NA,
                group=character(), valueClass=character())

    makeStandardGeneric(f, fdef)

    generic.skeleton(name, fdef, fdefault)

    defaultDumpName(generic, signature)

    getAllMethods(f, libs=search())

    setAllMethodsSlot(mlist)

    doPrimitiveMethod(name, def, call=sys.call(-1), ev=sys.frame(-2))

    conformMethod(signature, mnames, fnames)

    getGeneric(f, mustFind=FALSE)

    getGroup(fdef, recursive=FALSE)

    getGroupMembers(f, fdef = getGeneric(f))
    setGroupMembers(f, members, fdef = getGeneric(f))

    matchSignature(names, signature, fun)

    ## manage method metadata
    getFromMethodMetaData(name)

    assignToMethodMetaData(name, value)

    removeFromMethodMetaData(name)

    removeMethodsObject(f, where)

    findUnique(what, doFind, message)

    MethodAddCoerce(method, argName, thisClass, methodClass)

    is.primitive(fdef)

    copyEnvironment(object, exceptions)

    cacheMetaData(envir, attach = TRUE)

    cacheGenericsMetaData(generics, attach = TRUE, envir)

    setPrimitiveMethods(f, fdef, code, generic, mlist)

    printNoClass(x, digits, quote, na.print, print.gap, right, ...)

    print.default(x, ...)

    missingArg(symbol, envir = parent.frame())

    balanceMethodsList(mlist, args, check = TRUE)

    sigToEnv(signature)

    rematchDefinition(definition, generic, mnames, fnames)
    unRematchDefinition(definition)

### Summary of Functions

`makeGeneric`:
  Makes a generic function object corresponding to the given function name and optional definition.
`makeStandardGeneric`:
  a utility function that makes a valid function calling standardGeneric for name f. Works (more or less) even if the actual definition, fdef, is not a proper function, that is, it's a primitive or internal.
`conformMethod`:
  If the formal arguments, `mnames`, are not identical to the formal arguments to the function, `fnames`, `conformMethod` determines whether the signature and the two sets of arguments conform, and returns the signature, possibly extended.

  The method assignment conforms if either method and function have identical formal argument lists. It can also conform if the method omits some of the formal arguments of the function but: (1) the non-omitted arguments are a subset of the function arguments, appearing in the same order; (2) there are no arguments to the method that are not arguments to the function; and (3) the omitted formal arguments do not appear as explicit classes in the signature.

`defaultDumpName`:
  the default name to be used for dumping a method.
`getAllMethods`:
  a generic function (with methods) representing the merge of all the versions of `f` on the specified packages (anything on the current search path by default).

  If the generic `f` has a group generic, methods for this group generic (and further generations of group generics, if any) are also merged.

  The merging rule is as follows: each generic is merged across packages, and the group generics are then merged, finally adding the directly defined methods of `f`.

  The effect of the merging rule is that any method directly defined for `f` on any included package overrides a method for the same signature defined for the group generic; similarly for the group generic and its group, if any, etc.

  For `f` or for a specific group generic, methods override in the order of the packages being searched. A method for a particular signature on a particular package overrides any methods for the same signature on packages later on in the list of packages being searched.

  The slot "allMethods" of the merged methods list is set to a copy of the methods slot; this is the slot where inherited methods are stored.

`doPrimitiveMethod`:
  do a primitive call to builtin function `name` the definition and call provided, and carried out in the environment `ev`.

  A call to `doPrimitiveMethod` is used when the actual method is a .Primitive. (Because primitives don't behave correctly as ordinary functions, not having either formal arguments nor a function body).

`getGeneric`:
  return the definition of the function named f as a generic.

  If there is no definition in the current search list, throws an error or returns NULL according to the value of mustFind.

  Primitive functions are dealt with specially, since there is never a formal generic definition for them. The value returned is the formal definition used for assigning methods to this primitive. Not all primitives can have methods; if this one can't, then `getGeneric` returns `NULL` or throws an error.

`getGroup`:
  return the groups to which this generic belongs.

  If `recursive=TRUE`, also all the group(s) of these groups.

`getGroupMembers`, `setGroupMembers`:
  Get or set the known members of the group generic function `f`.
`matchSignature`
  Matches the signature object (a partially or completely named subset of the arguments of `fun`), and return a vector of all the classes in the order specified by `names`. The classes not specified by `signature' will be `"ANY"` in the value, but extra trailing `"ANY"`'s are removed. When the input signature is empty, the returned signature is a single `"ANY"` matching the first formal argument (so the returned value is always non-empty).

  The formal arguments of `fun` must agree with `names` (usually the formal arguments of the generic function) as well, and `matchSignature` checks this.

`getMethodsMetaData`, `assignMethodsMetaData`, `mlistMetaName`:
  utilities to manage methods list objects in a particular environment. Not to be called directly.
`getFromMethodMetaData`, `assignToMethodMetaData`, `removeFromMethodMetaData`
  Functions to manage the session metadata for methods. Don't call these directly.
`MethodAddCoerce`
  Possibly modify one or more methods to explicitly coerce this argument to `methodClass`, the class for which the method is explicitly defined. Only modifies the method if an explicit coerce is required to coerce from `thisClass` to `methodClass`.
`is.primitive`
  Is this object a primitive function (either a builtin or special)?
`removeMethodsObject`:
  remove the metadata object containing methods for `f`.
`findUnique`:
  Find the first position on the search list containing object `what`; if more than one is found, a warning message is generated, using `message` to identify what was being searched for.

  If `doFind` is supplied, it's the version of `find` used to do the search (e.g., `findFunction`.

`cacheMetaData`, `cacheGenericsMetaData`, `setPrimitiveMethods`:
  Utilities for ensuring that the session-scope information about class and method definitions is up to date. Should normally be called automatically whenever needed (for example, when a method or class definition changes, or when a package is attached or detached.

  The `environment` must be one of the environments on the current search list; note in particular that even on detaching (`attach=FALSE`), the environment will normally still be on the search list.

  The `setPrimitiveMethods` function resets the caching information for a particular primitive function. Don't call it directly.

`printNoClass`,`print.default`:
  `printNoClass` is equivalent to the version of `print.default` in the base package. The methods package overrides the latter function to provide meaningful printing for formally defined classes, and `printNoClass` is used to get the original default printing.
`missingArg`:
  Returns `TRUE` if the symbol supplied is missing from the call corresponding to the environment supplied (by default, environment of the call to `missingArg`). If `eval` is true, the argument is evaluated to get the name of the symbol to test. Note that `missingArg` is closer to the ``blue-book'' sense of the `missing` function, not that of the current R base package implementation. But beware that it works reliably only if no assignment has yet been made to the argument. (For method dispatch this is fine, because computations are done at the begining of the call.)
`balanceMethodsList`:
  Called from `setMethod` to ensure that all nodes in the list have the same depth (i.e., the same number of levels of arguments). Balance is needed to ensure that all necessary arguments are examined when inherited methods are being found and added to the `allMethods` slot. No actual recomputation is needed usually except when a new method uses a longer signature than has appeared before.

  Balance requires that all methods be added to the generic via `setMethod` (how else could you do it?) or by the initial `setGeneric` call converting the ordinary function.

`sigToEnv`:
  Turn the signature (a named vector of classes) into an environment with the classes assigned to the names. The environment is then suitable for calling `MethodsListSelect`, with `evalArgs=FALSE`, to select a method corresponding to the signature. Usually not called directly: see `selectMethod`.

`.saveImage`:
  Flag, used in dynamically initializing the methods package from `.First.lib`

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