checking in before refactoring interpolation

exec_extra/consts.go

@@ -0,0 +1,34 @@
+package exec_extra
+
+var (
+	StructTagCmdArgs string = "cmdarg"
+)
+
+var (
+	/*
+		CmdArgsOptPreferShort, if specified, prefers the "short" argument over "long" if both are specified.
+		The default is to prefer long.
+
+		Can be specified per-field via the `prefer_short` option (no value/value ignored).
+	*/
+	CmdArgsOptPreferShort cmdArgOpt = func(opts *cmdArgsOpts) (err error) {
+		opts.preferShort = true
+		return
+	}
+
+	/*
+		CmdArgsOptShortEquals, if specified, renders short flags *with* an equals sign
+		(if using POSIX args).
+
+		Has no effect if using Windows traditional syntax or if there is no value for the field.
+	*/
+	CmdArgsOptShortEquals cmdArgOpt = func(opts *cmdArgsOpts) (err error) {
+		opts.preferShort = true
+		return
+	}
+
+	CmdArgsOptLongNoEquals cmdArgOpt = func(opts *cmdArgsOpts) (err error) {
+		opts.preferShort = true
+		return
+	}
+)

exec_extra/consts_windows.go

@@ -0,0 +1,45 @@
+package exec_extra
+
+var (
+	/*
+		CmdArgsOptForcePosix forces the resulting command string to use "POSIX-style" flag notation.
+
+		Traditionally, Windows used flags like `/f` instead of POSIX `-f`, `/c:value` instead of `-c value`
+		or `-c=value`, etc.
+
+		If this option is passed, either to GetCmdFromStruct() or for a specific field via the
+		tag defined by StructTagCmdArgs (option `force_posix`, no value/value ignored), then the
+		POSIX-style flag syntax will be used instead.
+
+		Note that on Windows runtime, the default is to use the traditional slash-based syntax.
+		If you are generating command strings for Powershell or third-party software, you probably
+		want to use this option.
+
+		See also the inverse of this option, CmdArgsOptForceNoPosix.
+	*/
+	CmdArgsOptForcePosix cmdArgOpt = func(opts *cmdArgsOpts) (err error) {
+		opts.forcePosix = true
+		return
+	}
+
+	/*
+		CmdArgsOptForceNoPosix forces the resulting command string to use "traditional Windows" flag notation.
+
+		Traditionally, Windows used flags like `/f` instead of POSIX `-f`, `/c:value` instead of `-c value`
+		or `-c=value`, etc.
+
+		If this option is passed, either to GetCmdFromStruct() or for a specific field via the
+		tag defined by StructTagCmdArgs (option `force_no_posix`, no value/value ignored), then the
+		Windows-style flag syntax will be used instead.
+
+		Note that on Windows runtime, the default is to use the traditional slash-based syntax.
+		If you are generating command strings for Powershell or third-party software, you probably
+		want to use CmdArgsOptForcePosix instead.
+
+		See also the inverse of this option, CmdArgsOptForcePosix.
+	*/
+	CmdArgsOptForceNoPosix cmdArgOpt = func(opts *cmdArgsOpts) (err error) {
+		opts.forcePosix = false
+		return
+	}
+)

exec_extra/func.go

@@ -1,31 +0,0 @@
-/*
-   SysUtils - a library to assist with various system-related functions
-   Copyright (C) 2020  Brent Saner
-
-   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, either version 3 of the License, or
-   (at your option) any later version.
-
-   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 <https://www.gnu.org/licenses/>.
-*/
-
-package exec_extra
-
-import (
-	"os/exec"
-)
-
-func ExecCmdReturn(cmd *exec.Cmd) (exitStatus int, err error) {
-	// https://stackoverflow.com/a/55055100/733214
-	err = cmd.Run()
-	exitErr, _ := err.(*exec.ExitError)
-	exitStatus = exitErr.ExitCode()
-	return
-}

exec_extra/funcs.go

@@ -0,0 +1,86 @@
+/*
+   SysUtils - a library to assist with various system-related functions
+   Copyright (C) 2020  Brent Saner
+
+   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, either version 3 of the License, or
+   (at your option) any later version.
+
+   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 <https://www.gnu.org/licenses/>.
+*/
+
+package exec_extra
+
+import (
+	"os/exec"
+)
+
+func ExecCmdReturn(cmd *exec.Cmd) (exitStatus int, err error) {
+	// https://stackoverflow.com/a/55055100/733214
+	err = cmd.Run()
+	exitErr, _ := err.(*exec.ExitError)
+	exitStatus = exitErr.ExitCode()
+	return
+}
+
+/*
+	GetCmdFromStruct takes (a pointer to) a struct and returns a slice of
+	strings compatible with os/exec.Cmd.
+
+	The tag name used can be changed by setting the StructTagCmdArgs variable in this module;
+	the default is `cmdarg`.
+
+	If the tag value is "-", the field will be skipped. Any other tag value(s) are ignored.
+
+	Tag value format:
+		<tag>:"<option>=<value>[,<option>[=<value>],<option>[=<value>]...]"
+	e.g.
+		cmdarg:"short=l,long=list"
+		cmdarg:"short=l"
+		cmdarg:"long=list"
+
+	If the tag value is "-", or <VAR NAME> is not provided, the field will be explicitly skipped.
+	(This is the default behavior for struct fields not tagged with `cmdarg`.)
+
+	If a cmdarg tag is specified but has no `short` or `long` option value, the field will be skipped entirely.
+	If a field's value is nil, it will be skipped.
+	Otherwise if a field's value is the zero-value, it will be skipped.
+
+	Recognized options:
+
+	* short - A short flag for the argument
+
+	e.g.:
+
+		struct{
+			// If this is an empty string, it will be replaced with the value of $CWD.
+			CurrentDir string `envpop:"CWD"`
+			// This would only populate with $USER if the pointer is nil.
+			UserName *string `envpop:"USER"`
+			// This will *always* replace the field's value with the value of $DISPLAY,
+			// even if not an empty string.
+			// Note the `force` option.
+			Display string `envpop:"DISPLAY,force"`
+			// Likewise, even if not nil, this field's value would be replaced with the value of $SHELL.
+			Shell *string `envpop:"SHELL,force"`
+			// This field will be untouched if non-nil, otherwise it will be a pointer to an empty string
+			// if FOOBAR is undefined.
+			NonExistentVar *string `envpop:"FOOBAR,allow_empty"`
+		}
+
+	If s is nil, nothing will be done and err will be errs.ErrNilPtr.
+	If s is not a pointer to a struct, nothing will be done and err will be errs.ErrBadType.
+*/
+func GetCmdFromStruct[T any](s T, opts ...cmdArgOpt) (cmdSlice []string, err error) {
+
+	// TODO
+
+	return
+}

exec_extra/types.go

@@ -0,0 +1,9 @@
+package exec_extra
+
+type cmdArgsOpts struct {
+	preferShort bool
+	forcePosix  bool
+	cmd         *string
+}
+
+type cmdArgOpt func(*cmdArgsOpts) (err error)

exec_extra/utils.go

@@ -0,0 +1,33 @@
+package exec_extra
+
+import (
+	`r00t2.io/sysutils/paths`
+)
+
+/*
+	CmdArgsWithBin returns a cmdArgsOpt that specifies program/executable/binary path `bin`,
+	ensuring that the resulting cmdSlice from GetCmdFromStruct() will return a ready-to-use slice.
+	(Otherwise the executable would need to be prepended to the resulting slice.)
+
+	Path normalization/canonziation can be enabled/disabled via normalizePath.
+*/
+func CmdArgsWithBin(bin string, normalizePath bool) (opt cmdArgOpt, err error) {
+
+	if normalizePath {
+		if err = paths.RealPath(&bin); err != nil {
+			return
+		}
+	}
+
+	opt = func(opts *cmdArgsOpts) (err error) {
+		/*
+			if opts.cmd == nil {
+				opts.cmd = new(string)
+			}
+		*/
+		*opts.cmd = bin
+		return
+	}
+
+	return
+}