Windows registry access made easy

by Finnian Reilly (modified: 2014 Mar 01)

    Contents
  1. Windows Registry Access
    1. Example 1
    2. Example 2
    3. Caveats

Windows Registry Access

A new module, wel-regedit-x.ecf, has been added to Eiffel-Loop libraries that provides a more abstract interface to the WEL classes for accessing/modifying the registry in Windows. The following examples illustrate it's use.

Example 1

The following code fragment illustrates iterating over the sub keys of a registry key (EL_ITERABLE_REGISTRY_KEYS) and accessing binary data. As it happens, only the first sub key is required in this instance. The code is part of a class for extracting the physical dimensions of the currently active display monitor. class EL_WEL_DISPLAY_MONITOR_INFO inherit EL_WEL_DISPLAY_MONITOR_API undefine default_create end EL_MODULE_WIN_REGISTRY undefine default_create end feature -- Access model: STRING -- Monitor model -- Example: IVM5601 local path_steps: EL_PATH_STEPS do -- Example device_id: "MONITOR\IVM5601\{4d36e96e-e325-11ce-bfc1-08002be10318}\0000" path_steps := primary_device.device_id Result := path_steps.i_th (2) end EDID: MANAGED_POINTER -- Extended display identification data -- See: http://en.wikipedia.org/wiki/Extended_display_identification_data feature {NONE} -- Implementation set_EDID_data require long_enough_device_id: primary_device.device_id.split ('\').count >= 2 local EDID_registry_path: EL_DIR_PATH display_keys: EL_ITERABLE_REGISTRY_KEYS do create display_keys.make (HKLM_enum_display.joined_dir_path (model)) across display_keys as key until key.cursor_index > 1 loop EDID_registry_path := HKLM_enum_display.joined_dir_steps (<< model, key.item.name.to_string_8, "Device Parameters" >>) end EDID := Win_registry.data (EDID_registry_path, "EDID") ensure has_EDID_data: EDID.count > 0 end feature {NONE} -- Constants HKLM_enum_display: EL_DIR_PATH once Result := "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\DISPLAY" end end

Example 2

The following code adds some registry entries for applications that make use of the embedded browser provided by class EV_WEB_BROWSER. It prevents the browser from emulating an early version of IE provoking JavaScript errors. It illustrates setting an integer value (DWORD) and removing a key value.

class EL_WEB_BROWSER_INSTALLER inherit EL_MODULE_WIN_REGISTRY EL_MODULE_EXECUTION_ENVIRONMENT feature -- Basic operations install do Win_registry.set_integer ( HKLM_IE_feature_browser_emulation, Execution.executable_name, Internet_explorer_major_version * 1000 + 1 ) end uninstall do Win_registry.remove_key_value (HKLM_IE_feature_browser_emulation, Execution.executable_name) end feature {NONE} -- Constants Internet_explorer_major_version: INTEGER local version: EL_ASTRING once across << "svcVersion", "Version" >> as key_name until Result > 0 loop version := Win_registry.string (HKLM_Internet_explorer, key_name.item) if not version.is_empty then Result := version.split ('.').first.to_integer end end end HKLM_Internet_explorer: EL_DIR_PATH once Result := "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer" end HKLM_IE_feature_browser_emulation: EL_DIR_PATH once Result := HKLM_Internet_explorer.joined_dir_path ("MAIN\FeatureControl\FEATURE_BROWSER_EMULATION") end end

Caveats

Unfortunately to use this module you have to compile the entire WEL GUI library even if you are only using it in a command line application. But if you have a decent PC it shouldn't be too noticeable.