Skip to content

Latest commit

 

History

History
 
 

cpptype

README.md

  • infos = Information about type plugin is in keys below
  • infos/author = Markus Raab elektra@libelektra.org
  • infos/licence = BSD
  • infos/provides = check
  • infos/needs =
  • infos/placements = presetstorage
  • infos/status = nodep memleak unfinished old obsolete
  • infos/metadata = check/type type check/type/min check/type/max
  • infos/description = type checker using COBRA data types

This plugin is obsolete: Please use the newtype plugin instead.

Introduction

This plugin is a type checker plugin using the CORBA data types.

A common and successful type system happens to be CORBA. The system is well suited because of the many well-defined mappings it provides to other programming languages.

The type checker plugin supports all basic CORBA types: short, unsigned_short, long, unsigned_long, long_long, unsigned_long_long, float, double, char, boolean, any and octet. When checking any it will always be successful, regardless of the content.

The metadata check/type can be used to override the type metadata. This can be useful if the type to check differs to the type for code generation or the highlevel API. In most cases though, type will be enough to specify.

Deprecation

empty and FSType are deprecated. Please use regular expressions or enums instead.

Sometimes the type should expresses that, for example, both an empty or another type is valid. This type checker allowed a space-separated list of types to expresses that. If any of those types match, the whole type was valid. For example, the type string empty equals the type any. This facility builds a union of the sets of instances existing types specify. It is now deprecated due to a more general sum type facility.

check/type/min and check/type/max are deprecated, please use the range plugin instead.

Example

# Mount the plugin
sudo kdb mount typetest.dump user/tests/cpptype dump cpptype

# Store a character value
kdb set user/tests/cpptype/key a

# Only allow character values
kdb setmeta user/tests/cpptype/key check/type char
kdb get user/tests/cpptype/key
#> a

# If we store another character everything works fine
kdb set user/tests/cpptype/key b
kdb get user/tests/cpptype/key
#> b

# If we try to store a string Elektra will not change the value
kdb set user/tests/cpptype/key 'Not a char'
# STDERR: .*error in the type plugin.*
# ERROR:  52
# RET:    5
kdb get user/tests/cpptype/key
#> b

# Undo modifications to the database
kdb rm user/tests/cpptype/key
sudo kdb umount user/tests/cpptype

Limitations

wchar is missing.

Enum and records are part of other plugins.

The CORBA type system also has its limits. The types string and enum can be unsatisfactory. While string is too general and makes no limit on how the sequence of characters is structured, the enumeration is too finite. For example, it is not possible to say that a string is not allowed to have a specific symbol in it. Combine this plugin with other type checker plugins to circumvent such limitations.