Fixes #11602: Add a method to compute and format output

tests/acceptance/30_generic_methods/variable_string_from_expression.cf

@@ -0,0 +1,54 @@
+#######################################################
+#
+# Read a file into a string
+#
+#######################################################
+
+bundle common acc_path
+{
+  vars:
+    "root" string => getenv("NCF_TESTS_ACCEPTANCE", 1024);
+}
+
+body common control
+{
+      inputs => { "${acc_path.root}/default.cf.sub", "${acc_path.root}/default_ncf.cf.sub", "@{ncf_inputs.default_files}" };
+      bundlesequence  => { configuration, default("${this.promise_filename}") };
+      version => "1.0";
+}
+
+#######################################################
+
+bundle agent init
+{
+  vars:
+    "tmp"         string => getenv("TEMP", 1024);
+    "three"       string => "3";
+}
+
+#######################################################
+
+bundle agent test
+{
+  methods:
+
+    "ph1" usebundle => variable_string_from_expression("prefix", "var1", "${init.three}*(2.0+3.0)", "%d");
+}
+
+#######################################################
+
+bundle agent check
+{
+  classes:
+
+    "ok_1" expression => "variable_string_from_expression_var1_kept.!variable_string_from_expression_var1_repaired.!variable_string_from_expression_var1_error";
+    "ok_var1" expression => strcmp("${prefix.var1}", "15");
+
+    "ok"  expression => "ok_1.ok_var1";
+
+  reports:
+    ok::
+      "$(this.promise_filename) Pass";
+    !ok::
+      "$(this.promise_filename) FAIL";
+}

tree/30_generic_methods/variable_string_from_expression.cf

@@ -0,0 +1,79 @@
+#####################################################################################
+# Copyright 2017 Normation SAS
+#####################################################################################
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, Version 3.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+#####################################################################################
+
+# @name Variable string from expression
+# @description Define a variable from an expression
+# @documentation To use the generated variable, you must use the form `${variable_prefix.variable_name}` with each name replaced with the parameters of this method.
+#
+# Be careful that using a global variable can lead to unpredictable content in case of multiple definition, which is implicitly the case when a technique has more than one instance (directive). 
+# Please note that only global variables are available within templates.
+#
+# ## Usage
+#
+# This function will evaluate a mathematical expression that may contain variables and format the result according to the provided formatt string.
+#
+# The formatting string uses the standard POSIX printf format.
+#
+# #### Examples
+#
+# If you use:
+#
+# ```
+# variable_string("prefix", "var", "10");
+# variable_string_from_expression("prefix", "sum", "2.0+3.0", "%d");
+# variable_string_from_expression("prefix", "product", "3*${prefix.var}", "%d");
+# ```
+#
+# The `prefix.sum` string variable will contain `5` and `prefix.product` will contain `30`.
+#
+# @parameter variable_prefix The prefix of the variable name
+# @parameter variable_name   The variable to define, the full name will be variable_prefix.variable_name
+# @parameter expression      The mathematical expression to evaluate
+# @parameter format          The format string to use
+# 
+# @class_prefix variable_string_from_expression
+# @class_parameter variable_name
+
+bundle agent variable_string_from_expression(variable_prefix, variable_name, expression, format)
+{
+  vars:
+      "old_class_prefix"  string => canonify("variable_string_from_expression_${variable_name}");
+      "promisers"          slist => { @{this.callers_promisers}, cf_null }, policy => "ifdefined";
+      "class_prefix"      string => canonify(join("_", "promisers"));
+      "args"              slist => { "${variable_prefix}", "${variable_name}", "${expression}", "${format}" };
+
+      # define the variable within the variable_prefix namespace
+      "temp" string => eval("${expression}");
+      "${variable_prefix}.${variable_name}" string => format("${format}", "${temp}");
+
+  classes:
+     "variable_defined" expression => isvariable("${variable_prefix}.${variable_name}");
+
+  methods:
+    !variable_defined::
+      "error"    usebundle => _classes_failure("${old_class_prefix}");
+      "error"    usebundle => _classes_failure("${class_prefix}");
+
+    variable_defined::
+      "success"  usebundle => _classes_success("${old_class_prefix}");
+      "success"  usebundle => _classes_success("${class_prefix}");
+
+    any::
+      "report"
+        usebundle  => _log("Set the string ${variable_prefix}.${variable_name} to the result of ${expression} formatted by '${format}'", "${old_class_prefix}", "${class_prefix}", @{args});
+}