13 Windows Registry

▼ |  | File: Racket File and Format Libraries

1 | Convertible: Data-Conversion Protocol
2 | gzip Compression and File Creation
3 | gzip Decompression
4 | zip File Creation
5 | zip File Extraction
6 | tar File Creation
7 | tar File Extraction
8 | tar+gzip File Extraction
9 | MD5 Message Digest
10 | SHA1 Message Digest
11 | GIF File Writing
12 | ICO File Reading and Writing
13 | Windows Registry
14 | Caching
| Bibliography
| Index

On this page:

get-resource
write-resource

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### 13`` Windows Registry

(require file/resource) | package: base

> > procedure
> > (get-resource |  | section |
> > |  | entry |
> > | [ | value-box |
> > |  | file |
> > |  | #:type type]) |
> → (or/c #f string? bytes? exact-integer? #t)
> section : string?
> entry : string?
> | value-box |  | : |  | (or/c #f (box/c (or/c string? bytes? exact-integer?)))
> |  |  | = |  | #f
> file : (or/c #f path-string?) = #f
> type : (or/c 'string 'bytes 'integer) = derived-from-value-box

Gets a value from the Windows registry or an ".ini" file. For backward compatibilty, the result is #f for platforms other than Windows. The registry is read when file is #f and when section is "HKEY_CLASSES_ROOT", "HKEY_CURRENT_CONFIG", "HKEY_CURRENT_USER", "HKEY_LOCAL_MACHINE", or "HKEY_USERS". When file is #f and section is not one of the special registry strings, then (build-path (find-system-path 'home-dir) "mred.ini") is read.

The resource value is keyed on the combination of section and entry. The result is #f if no value is found for the specified section and entry. If value-box is a box, then the result is #t if a value is found, and the box is filled with the value; when value-box is #f, the result is the found value.

The type argument determines how a value in the resource is converted to a Racket value. If value-box is a box, then the default type is derived from the initial box content, otherwise the default type is 'string.

Registry values of any format can be extracted. Values using the registry format REG_SZ are treated as strings, and values with the format REG_DWORD are treated as 32-bit signed integers. All other formats are treated as raw bytes. Data from the registry is converted to the requested type as follows:

- A REG_SZ registry value is converted to an integer using string->number (using 0 if the result is not an exact integer), and it is converted to bytes using string->bytes/utf-8.

- A REG_DWORD registry value is converted to a string or byte string via number->string and (for byte strings) string->bytes/utf-8.

- Any other kind of registry value is converted to a string or integer using bytes->string/utf-8 and (for integers) string->number.

Resources from ".ini" files are always strings, and are converted like REG_SZ registry values.

To get the “default” value for a registry entry, use a trailing backslash. For example, the following expression gets a command line for starting a browser:

> (get-resource "HKEY_CLASSES_ROOT"
> "htmlfile\\shell\\open\\command\\")

> > procedure
> > (write-resource |  | section |  |  |  |
> > |  | entry |  |  |  |
> > |  | value |  |  |  |
> > | [ | file |  |  |  |
> > |  | #:type type |  |  |  |
> > |  | #:create-key? create-key?]) |  | → |  | boolean?
> section : string?
> entry : string?
> value : (or/c string? bytes? exact-integer?)
> file : (or/c path-string? #f) = #f
> type : (or/c 'string 'bytes 'integer) = 'string
> create-key? : any/c = #f

Write a value to the Windows registry or an ".ini" file. For backward compatibilty, the result is #f for platforms other than Windows. The registry is written when file is #f and when section is "HKEY_CLASSES_ROOT", "HKEY_CURRENT_CONFIG", "HKEY_CURRENT_USER", "HKEY_LOCAL_MACHINE", or "HKEY_USERS". When file is #f and section is not one of the special registry strings, then (build-path (find-system-path 'home-dir) "mred.ini") is written.

The resource value is keyed on the combination of section and entry. If create-key? is false when writing to the registry, the resource entry must already exist, otherwise the write fails. The result is #f if the write fails or #t if it succeeds.

The type argument determines the format of the value written to the registry: 'string writes using the REG_SZ format, 'bytes writes using the REG_BINARY format, and 'dword writes using the REG_DWORD format. Any kind of value can be converted for any kind of type using the inverse of the conversions for get-resource.

When writing to an ".ini" file, the format is always a string, independent of type.

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