cleanup: use std::string in struct device

struct device is a core data structure and therefore shouldn't use QString.
QString stores as UTF-16 (which is a very questionable choice in itself).
However, the real problem is that this puts us in lifetime-management
hell when interfacing with C code: The UTF-16 has to be converted to
UTF-8, but when returning such a string, this puts burden on the caller
who has to free it. In fact, instead of looping over devices from C-code
we had a callback that sent down temporary C-strings with qPrintable.

In contrast, std::string is guaranteed to store its data as
contiguous null-terminated and C-compatible strings. Therefore,
replace the QString by std::string. Keep the QString just in
one place that formats a hexadecimal number to avoid any
potential change.

The disadvantage of using std::string is that it will crash
when constructed with a NULL argument, consistent with C-style
functions such as strcmp, etc. Arguably, NULL is different
from the empty string even though we treat both as the same.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

1 files changed, 7 insertions, 7 deletions

diff --git a/core/device.h b/core/device.h
index 910c77b90..90d67bb5e 100644
--- a/core/device.h
+++ b/core/device.h
@@ -16,6 +16,7 @@ extern void create_device_node(const char *model, uint32_t deviceid, const char
 extern void call_for_each_dc(void *f, void (*callback)(void *, const char *, uint32_t,
 						       const char *, const char *, const char *), bool select_only);
 extern void clear_device_nodes();
+const char *get_dc_nickname(const struct divecomputer *dc);
 
 #ifdef __cplusplus
 }
@@ -24,18 +25,18 @@ extern void clear_device_nodes();
 // Functions and global variables that are only available to C++ code
 #ifdef __cplusplus
 
-#include <QString>
+#include <string>
 #include <QVector>
 struct device {
 	bool operator==(const device &a) const;
 	bool operator!=(const device &a) const;
 	bool operator<(const device &a) const;
-	void showchanges(const QString &n, const QString &s, const QString &f) const;
-	QString model;
+	void showchanges(const std::string &n, const std::string &s, const std::string &f) const;
+	std::string model;
 	uint32_t deviceId;
-	QString serialNumber;
-	QString firmware;
-	QString nickName;
+	std::string serialNumber;
+	std::string firmware;
+	std::string nickName;
 };
 
 struct device_table {
@@ -43,7 +44,6 @@ struct device_table {
 	QVector<device> devices;
 };
 
-QString get_dc_nickname(const struct divecomputer *dc);
 extern struct device_table device_table;
 
 #endif