api: deprecate using space id in len

Part of #255

CHANGELOG.md

@@ -5,6 +5,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Changed
+* Deprecate using space id in `crud.len` (#255).
+
 ## [0.13.0] - 29-08-22
 
 ### Added

README.md

@@ -1037,13 +1037,15 @@ local result, err = crud.len(space_name, opts)
 
 where:
 
-* `space_name` (`string|number`) - name of the space as well
-  as numerical id of the space
+* `space_name` (`string`) - name of the space
 * `opts`:
   * `timeout` (`?number`) - `vshard.call` timeout (in seconds)
 
 Returns number or nil with error.
 
+Using space id instead of space name is also possible, but
+deprecated and will be removed in future releases.
+
 **Example:**
 
 Using `memtx`:

crud/len.lua

@@ -1,6 +1,7 @@
 local checks = require('checks')
 local errors = require('errors')
 local vshard = require('vshard')
+local log = require('log')
 
 local utils = require('crud.common.utils')
 local dev_checks = require('crud.common.dev_checks')
@@ -43,6 +44,11 @@ function len.call(space_name, opts)
 
     opts = opts or {}
 
+    if type(space_name) == 'number' then
+        log.warn('Using space id in crud.len is deprecated and will be removed in future releases.' ..
+                 'Please, use space name instead.')
+    end
+
     local space = utils.get_space(space_name, vshard.router.routeall())
     if space == nil then
         return nil, LenError:new("Space %q doesn't exist", space_name)