polish up the fix for #576

Author: bhaller

EidosScribe/EidosHelpFunctions.rtf

@@ -6686,6 +6686,24 @@ The task keys recognized, and the tasks they govern, are:\
 \f3\fs20 \cf2 Typically, a dictionary of task keys and thread counts is read from a file and set up with this function at initialization time, but it is also possible to change new task thread counts dynamically.  If Eidos is not configured to run multithreaded, this function has no effect.\
 \pard\pardeftab397\li720\fi-446\ri720\sb180\sa60\partightenfactor0
 
+\f1\fs18 \cf2 (string$)readLine(void)\
+\pard\pardeftab397\li547\ri720\sb60\sa60\partightenfactor0
+
+\f0\b\fs20 \cf2 Reads a line of input from the \'93standard input\'94 file.
+\f3\b0   This function is intended to allow for communication between a running Eidos script (such as a SLiM simulation) and an external process that is sending input to it.  It reads one line from the standard input and returns it as a singleton 
+\f1\fs18 string
+\f3\fs20 .  This is done with the C++ function 
+\f1\fs18 std::getline()
+\f3\fs20 , using the 
+\f1\fs18 std::cin
+\f3\fs20  file.  If that call returns false (typically because the end-of-file was reached or there was a read error of some kind), the empty string 
+\f1\fs18 ""
+\f3\fs20  will be returned.  The 
+\f1\fs18 system()
+\f3\fs20  function can also be helpful for related situations.\
+This function will raise an error if called in a GUI environment such as EidosScribe, SLiMgui, or SLiMguiLegacy, since there is no standard input set up for the running script in those environments.\
+\pard\pardeftab397\li720\fi-446\ri720\sb180\sa60\partightenfactor0
+
 \f1\fs18 \cf2 (void)rm([Ns\'a0variableNames\'a0=\'a0NULL])\
 \pard\pardeftab397\li547\ri720\sb60\sa60\partightenfactor0
 

QtSLiM/help/EidosHelpFunctions.html

@@ -648,6 +648,9 @@
 "UNIQUE_MUTRUNS"<span class="Apple-tab-span">	</span></span>uniquing mutation runs (internal bookkeeping)<span class="s2"><br>
 "SURVIVAL"<span class="Apple-tab-span">	</span></span>survival evaluation (no callbacks)</p>
 <p class="p5">Typically, a dictionary of task keys and thread counts is read from a file and set up with this function at initialization time, but it is also possible to change new task thread counts dynamically.<span class="Apple-converted-space">  </span>If Eidos is not configured to run multithreaded, this function has no effect.</p>
+<p class="p4">(string$)readLine(void)</p>
+<p class="p5"><b>Reads a line of input from the “standard input” file.</b><span class="Apple-converted-space">  </span>This function is intended to allow for communication between a running Eidos script (such as a SLiM simulation) and an external process that is sending input to it.<span class="Apple-converted-space">  </span>It reads one line from the standard input and returns it as a singleton <span class="s2">string</span>.<span class="Apple-converted-space">  </span>This is done with the C++ function <span class="s2">std::getline()</span>, using the <span class="s2">std::cin</span> file.<span class="Apple-converted-space">  </span>If that call returns false (typically because the end-of-file was reached or there was a read error of some kind), the empty string <span class="s2">""</span> will be returned.<span class="Apple-converted-space">  </span>The <span class="s2">system()</span> function can also be helpful for related situations.</p>
+<p class="p5">This function will raise an error if called in a GUI environment such as EidosScribe, SLiMgui, or SLiMguiLegacy, since there is no standard input set up for the running script in those environments.</p>
 <p class="p4">(void)rm([Ns variableNames = NULL])</p>
 <p class="p5"><b>Removes variables</b> from the Eidos namespace; in other words, it causes the variables to become undefined.<span class="Apple-converted-space">  </span>Variables are specified by their <span class="s2">string</span> name in the <span class="s2">variableNames</span> parameter.<span class="Apple-converted-space">  </span>If the optional <span class="s2">variableNames</span> parameter is <span class="s2">NULL</span> (the default), <i>all</i> variables will be removed (be careful!).</p>
 <p class="p5">In SLiM 3, there was an optional parameter <span class="s2">removeConstants</span> that, if <span class="s2">T</span>, allowed you to remove defined constants (and then potentially redefine them to have a different value).<span class="Apple-converted-space">  </span>The <span class="s2">removeConstants</span> parameter was removed in SLiM 4, since the <span class="s2">defineGlobal()</span> function now provides the ability to define (and redefine) global variables that are not constant.</p>

VERSIONS

@@ -19,6 +19,7 @@ development head (in the master branch):
 	fix various bugs involving conflicts between defined constants and other symbols, including #573 and #574; this sets new definition rules that could break some existing scripts (but is unlikely to)
 	fix #575, QtSLiM terminates early when single-stepping with a rescheduled script block
 	fix #579, crash in models with (a) tree-seq recording, (b) multiple chromosomes, AND (c) rejection of proposed offspring in modifyChild()
+	add readLine() function for obtaining stdin input to running models, thanks to Chris Talbot
 
 
 version 5.1 (Eidos version 4.1):

eidos/eidos_functions_files.cpp

@@ -225,17 +225,15 @@ EidosValue_SP Eidos_ExecuteFunction_readFile(const std::vector<EidosValue_SP> &p
 //	(string$)readLine(void)
 EidosValue_SP Eidos_ExecuteFunction_readLine(const std::vector<EidosValue_SP> &p_arguments, EidosInterpreter &p_interpreter)
 {
-#pragma unused (p_arguments)
+#pragma unused (p_arguments, p_interpreter)
 
-#ifdef EIDOS_GUI
-	EIDOS_TERMINATION << "ERROR (Eidos_ExecuteFunction_readLine): function readLine() is not available in GUI environments (SLiMgui, SLiMguiLegacy, or EidosScribe)." << EidosTerminate(nullptr);
-#endif
-
 	// This function was implemented by Chris Talbot 11/19/25 for use in reinforcement learning environments.
 	// Associated with issue #576.
 
-	EidosValue_SP result_SP(nullptr);
-	
+#ifdef EIDOS_GUI
+	// Cannot be called inside a GUI since there is (presumably) no stdin set up for the script to read.
+	EIDOS_TERMINATION << "ERROR (Eidos_ExecuteFunction_readLine): function readLine() is not available in GUI environments (SLiMgui, SLiMguiLegacy, or EidosScribe)." << EidosTerminate(nullptr);
+#else
 	// Read a single line from stdin (command-line mode with interactive terminal)
 	std::string line;
 
@@ -245,15 +243,14 @@ EidosValue_SP Eidos_ExecuteFunction_readLine(const std::vector<EidosValue_SP> &p
 		if (!line.empty() && line[line.size() - 1] == '\r')
 			line.pop_back();
 
-		result_SP = EidosValue_SP(new (gEidosValuePool->AllocateChunk()) EidosValue_String(line));
+		return EidosValue_SP(new (gEidosValuePool->AllocateChunk()) EidosValue_String(line));
 	}
 	else
 	{
 		// EOF or error reading from stdin; return empty string
-		result_SP = EidosValue_SP(new (gEidosValuePool->AllocateChunk()) EidosValue_String(""));
+		return gStaticEidosValue_StringEmpty;
 	}
-	
-	return result_SP;
+#endif
 }
 
 //	(string$)setwd(string$ path)